In order to study the response characteristics of variable cam phaser (VCP) under each operating parameter, a test bench was built up, and the methods for calculating the dynamic response time of VCP were put forward. The response time of the maximal VCP advance and retard position, under operating parameter include engine speed, hydraulic oil’s pressure and temperature, can be measured. The experimental results indicate that response speed under the advance direction regulating of VCP is less than retard direction. Engine speed doesn’t have much prominent effect on VCP response speed. As the increase of oil’s temperature, the response speed become faster, but the rate of change is decreasing when the temperature higher than 70℃. The response speed augments as the oil’s pressure increases, especially in low pressure (lower than 0.4MPa).