The constructed engineering bacteria E.coli DH5a that contain plasmid pJGWl-hGCSF and pGPl-2 were cultured up to 140 generations. The antibiotics resistance and expressed protein level of rhG-CSF of the engineering bacteria is very stable. The recomhinant plasmids of pJGWl-hGCSF and pGPl-2 of different generations also showed the same electrophoretic patterns after restriction enzyme cleavage as those of the primary recombinant bacteria.