China has made a major investment in biotechnology research. Genetically modified (GM) cotton is widely adopted and the list of GM technologies in trials is impressive. At the same time there is an active debate on when China should commercialize its GM food crops. The overall goal of this paper is to provide an economy-wide assessment of these issues under various scenarios. Based on a unique data from empirical micro-level study and field trial in China and a modified GTAP model, our results indicate that the development of biotechnology has an important impact on China's production, trade and welfare. Welfare gains far outweigh the public biotechnology research expenditures. Most gains occur inside China. Policy makers should put less weight on the international dimension in making their decisions on biotechnology development.