Abstract: The stabilities of pBV220GM-CSF were observed in continuous cultures and fermenter culture.The E. coli with pBV220GM-CSF was consecutively cultured on LB plates with ampicillin;fed batch culture was made and GM-CSF was expressed by temperature inducing in ampicillin free media.The plasmids were stable in E. coli and the ability of expression and biological activity of GM-CSF was without obvious changes after 10,25,50 and 100 generational culture.But it was unstable at 42℃ inducing expression.This result showed that the plasmids of pBV220GM-CSF were stable in E. coli under antibiotics pressures.The suitable condition for large scale production should be explored.