A numerical simulation model of response velocity for engine VVT cam phaser was built by using AMESim software. Based on the experimental design and correlation analysis, the reliability of model was verified and the influencing mechanism of each key parameter on response velocity was studied. The study found that the primary factors of phaser response velocity were the blade force arm, blade thickness and preload. The influence of secondary factors was complex and nonlinear in the full-plane working condition. The blade thickness had a little influence on response velocity when the blade force arm was relatively large. The phaser response velocity would not change significantly with the increase of preload when the blade force arm and blade thickness increased.