The dynamic relationships between price and volume of CSI 300 stock index futures are empirically examined based on 5 minutes high frequency transaction price and volume data of CSI 300 stock index futures contracts，and the results show that there is obviously positive direction relationship between price volatility and trading volume and between relative trading volume and relative position volume，but there is significantly negative direction relation with position volume，that there is obviously positive relationship between the volatility and expected trading volume or unexpected trading volume，furthermore，the positive influence of unexpected trading volume is bigger，that there is significantly negative relationship between the volatility and expected position volume or unexpected position volume，furthermore，the negative influence of unexpected position volume is bigger，that the influence of the change of trading volume and position volume on the volatility of stock index futures price is asymmetric，and that the influence of the shock of positive trading volume and position volume is bigger than that of negative trading volume and position volume，i.e. the influence on price volatility is bigger when unexpected trading volume and unexpected position volume are positive. The supervisors and investors in stock index futures market can analyze the changing trends of the implicit indicators such as price volatility and market risk and so on by monitoring explicit indicators such as trading volume，position volume，relatively trading volume，relative position volume and so on as well as their changes in order to implement proper supervising policies and trading policies.