According to the dynamic model of Vertical Cavity Surface Emitting Laser(VCSEL) with delay optical feedback，its chaotic dynamic behaviors were discussed by numerical simulation.And the influence of the external cavity length and optical feedback strength on the dynamic was analyzed.The results show that laser with short external cavity will come back to frequency-locked state after chaos.Laser with long external cavity will come back to period 1 instead of the locked state after chaos.When the external cavity is 3.0 cm，with optical feedback strength increasing，laser turns into chaos by bifurcation，and it can also get period 12 window in chaos.The research results have some theoretical reference value on practical applications.