The main factors affecting the crystallization in vitamin C（VC）industrial production were analyzed. Combining with the crystallization theory, actual production operation was researched，every key factor was analyzed.The optimal crystallization control method forming the suitable final product size was found out. A perfect crystallization control operation was established, the reasonably plan and product family were developed, an expansion analysis model of customer requirements was proposed based on ontology description to mine and predict customer requirements. The current market environment of VC was analyzed, the demand of the market and the users were described.