In this paper, the output dynamic performance of a voltage controlled constant current source based on the wide used model is researched. It is found that the main factors are integral capacitor and feedback amplification when the load resistor and output current is not changed; the main factor is the value of load resistor when the output current is in a certain range, while the current affection is very small. So the main factors are integral capacitor, feedback amplification and the load resistor. Finally, based on the design requirement of practical circuits, a solution is put forward that makes the dynamic performance better, and it proves the correctness of the conclusion by the simulation and test results of the practical circuit.