Abstract: In this study,CHO cell,which can express antibody fusion protein of human tumor necrosis factor receptor-Fc- people IgG,was used as research object.The effect of three important factors on the cell density,activity,expression level and percentage of polymers were investigated,including:the hydrolysate:0.5% yeast extract,0.5% cereal hydrolysate,0.5% soyprotein hydrolysate,0.5% phytone;the lipid:10 mmol/L phosphatidyl choline,10 mg/L ethanolamine,0.05% intralipid;the hormone substances:10 μmol/L hydrocortisone (adrenocortical hormone),10 mg/L insulin,20 nM progesterone (steroid hormones).The results showed that 0.5% yeast hydrolysate,10 mg/L ethanolamine and 0.05% intralipid in lipid,10 mg/L insulin can significantly improve the density,activity and the protein expression level of CHO cells.

Key words: CHO cells, serum free medium, cell vitality, protein expression level