AGC control technology is one of the key techniques used in modern rolling mill, the effect of which has influence on the accuracy of the product. On the base of analysing system composition and dynamic characteristics of the main dynamic emelent, a danamic simulation model is put forward,and then dynamic simultion for the hydraulic AGC system of 3340 rolling mill is implemented. Then, it lays a foundation for the design of rolling system and the dynamic simulation of the rolling process.