Abstract: Objective: This study observed the effects of poly（3 hydroxybutyrate co 3 hydroxyhexanoate）,p（3HB co 3HH）on biobehavior of mammiferous bone marrow stem cells（BMSCs） and the feasibility of p（3HB co 3HH） as a new type of biodegradable materials in tissue engineering.Methods: The BMSCs of canine were cultured in the lixivium of p（3HB co 3HH） in DMEM containing 15% fetal bovine serum Cell growth curve was protracted according to the sum of cells every day The toxicity of the lixivium to BMSCs was mensurated using MTT test The stages of cell cycle were analyzed with flow cytometry（FCM） The configuration of BMSCs inoculated on the film of p（3HB co 3HH） was observed under microscope.Results: The cell growth curve showed that the sum of the cells cultured with the lixivium was higher than cultured without the lixivium from 2 to 5 days In the presence of the lixivium, the relative growth rate（RGR） of cultured BMSCs was 102% at 96 hours（t test, P ＞0 05）,and the toxicity grade of the lixivium to BMSCs was 0.scale The results of FCM indicated that BMSCs in proliferating phase was 22 18% in cultured with the lixivium and it was 16 12% in control group On the film of p（3HB co 3HH）,the appearance of BMSCs was fibroblastoid and clustered Conclusions:The lixivium of p（3HB co 3HH）was innocuous to mammiferous BMSCs and prompted BMSCs to proliferate In the future, p（3HB co 3HH） may be applied in tissue engineering