It is not guaranteed your company and the product has a big market in China. This must be verified before investing lots resources in China just to find out that the profitable market does not actually exist.
After market research you know if there is a feasible market, who are your customers, where they are, and much more. You will gain valuable information to base your decision where to start your China operations and how. It is also possible that you will discover that the business you thought would be great is impossible in China. In this situation, you can shift your focus to more feasible markets without first struggling in China for nothing.