Purpose　The aim is to study the influence factors of recombinant E.coli cell growth,product expression and purification,in order to raise the product rate of rhGM-CSF.Methods　Three pH media were planed to observe the effects of pH on E.coli cell growth and expression with the indexes of the cell density and expression level.The influences of various treatments on product rate were observed with the indexes of the volume and purity of inclusion bodies and the yield,purity,activity of product.Using SDS-PAGE method for analysis of purity.The product bioactivity was determined by using TF1 cell and MTT colorimetric method.Results　The cell density in the medium pH 7.0 was 2.22 g/L;the product expression rate was 23%.It was two times higher than other pH media.The inclusion body prepared by bacteria without freezing store was 2.5 times volume than freezing store.During renatura-tion PEG 4000 could raise 0.8 times active product.The optimum conditions used rhGM-CSF product rate could raise 8 times.Concluston　The product rate of rhGM-CSF expressed in E.coli was affected by many factors.The optimum condition for culture,expression and purification could raise quite a number of product rate.