There are a few steps that you can take to protect your product rights if you are concerned about having your intellectual property stolen in China. You should consider doing all of the following before you begin manufacturing in China:

• Engage legal counsel that has knowledge of patent law in the US & China,like Hermax Intellectual Property which is a professional IP law firm in China handles the search, application, registration, translation,lawsuit,enforcement and other related services of trademarks, patents, design and copyright.
• Protect your designs in your home market (patent, trademark, etc.): Filing patents and trademarks can be expensive, but it is a worthwhile investment if you have to defend your right to the product later.
• Get signed exclusivity contracts from your suppliers: Again, if you are dealing with sourcing in China (a common practice that is often demanded by Chinese manufacturers) this will be very difficult.  If you are sourcing from the US, this will be less of a challenge.
• Look at the customers of a factory: Don't send sensitive designs to factories that have many larger customers that might want your product.
• Use multiple factories for components and do final assembly somewhere else: This will keep companies who may steal from having access to all your parts, and knowledge on how you do the assembly for your product.