Objective To study the factors influencing the mechanical properties of the degradable chain expanded PLA polymer. Methods Using GB 9641 88 to make the chain expanded PLA polymer into dumbbell shaped samples , the tensile strength was tested at a speed of 5mm/min by a universal testing machine of high polymer under different conditions of temperature ,time, molecular weight of chain expanding agent , PLA and PCL.Results In the course of chain expanding reaction the mixing temperature , mixing period , curing temperature , curing period , the molecular weight of the chain expand agent , the cross linking agent and PLA each had an influence on the tensile strength of the chain expanding PLA polymer. Conclusion The maximum tensile strength was 24.47 MPa when the ratio of PLA to PCL period equaled to 1∶4 , mixing temperature was 100°C , mixing period was 4min , curing temperature was 130°C , curing period was 6h , the molecular weight of chain expanding agent A , cross-linking agent 1 and PLA.