After years of relying on legal and political muscle to fight rampant piracy in China, big software companies have started wielding a new weapon: lower prices. And the early results are encouraging.

Software companies including Microsoft Corp. and Autodesk Inc. have seen unit sales jump since lowering prices to lure users away from pirated copies, executives said in interviews.

For instance, Autodesk, which makes AutoCAD and other design software, saw its number of licenses in China more than double to an estimated 300,000 as of July after it slashed local software prices last year, said Patrick Williams, Autodesk's senior vice president for the Asia-Pacific region.

The U.S. company's prices in China are now about half the level in the U.S., compared with about 20% to 30% lower before last year's reduction. Autodesk sells its flagship AutoCAD 2011 software on its U.S. website starting at $3,975.

The notion that lower prices could attract more customers might seem obvious, but for many in the software industry in China it represents a big change of heart.

Microsoft, for example, long kept retail prices for their software here close to levels in the U.S.—even though average incomes in China are a fraction of those in America—arguing there was no point trying to compete with pirated versions that sold for only a dollar or two.

The companies are starting to recognize, though, that at least some consumers in China are willing to pay for legitimate products at the right price. They also recognize that focusing on legal action to fight piracy has had limited effectiveness.

Microsoft last year started selling a stand-alone version of Windows 7 Home Basic, an entry-level version of its latest operating system, to consumers in China for 399 yuan, or about $59. That's less than a third of the $199.99 starting price for Windows 7 in the U.S.

Lower consumer prices have "definitely" boosted Microsoft's unit sales in China, said Simon Leung, Microsoft's chief executive for greater China, though he declined to provide details. He said the lower pricing helps discourage piracy, though it doesn't eliminate the problem.

"When you have a lower price your margin gets squeezed," he said. But "we have so much room to improve, so the volume will make it up."

Companies in other industries have also recognized many Chinese consumers require lower prices. Foreign auto makers like General Motors Corp. and Nissan Motor Co. are designing smaller, cheaper models to target Chinese consumers just becoming affluent enough to afford a car. And cellphone maker Nokia Corp. is known in China for selling lower-priced models to build up its market share among new phone buyers.

"It seems a reasonable approach to adjust software pricing according to the average income levels of different countries," said Ni Guangnan, a senior academic at the Chinese Academy of Engineering, who was critical of Microsoft when it took aim at copyright violators in 2008 by offering a Windows XP update that would turn users' screens black if it detected their operating system was illegitimate.

Piracy has made China one of the world's most frustrating markets for software companies, even as business has boomed for companies that sell other, more tangible consumer goods.

China is the world's second-largest personal-computer market, according to market researcher IDC, with shipments expected to jump 25% to 67 million units this year, behind the 78 million units in the U.S.

But IDC says China will be the No. 8 software market this year, with spending on packaged software expected to be about $5.8 billion—just a fraction of the projected spending of $143.6 billion in the U.S.

Still, the problem has started to improve in recent years. The Business Software Alliance, an industry advocacy group, and IDC estimated that 79% of the PC software installed in China last year was pirated, down from 86% in 2005. It's unclear how much of a role lower prices might have played in that shift.

Lowering retail prices is no panacea. It doesn't affect some of the biggest piracy culprits in China—big corporations, including some owned by the government, that often use far more copies of particular pieces of software than they actually pay for.

But executives say it puts a dent in the pirates' business, and helps cultivate a larger group of consumers who are accustomed to using legitimate software. "We want to lower the bar of legalization as much as possible," said Mr. Williams of Autodesk.

Adobe Systems Inc., a maker of graphics software such as its Creative Suite, has sold the simplified Chinese-language versions of its products for about 20% less than U.S. prices since 2006.

The lower prices can make Chinese buyers "more willing to invest," but companies also must be educated to remove their reservations about paying for software, Ng Yew Hwee, managing director for Adobe in Greater China, said in a recent interview.