Objective To study the optimization process of matching conditions using glutaraldehyde (GDA) as crosslinking agent of hemoglobin based oxygen carriers (HBOCs),to further reduce the average molecular weight and the content of super-weight molecular,and improve the conversion ratio of polymerization.Methods The orthogonal designs were done on the basis of the previous single influencing factor research of human placenta hemoglobin crosslinking GDA.Three factors were selected including molar ratio of GDA to hemoglobin,mass concentration of hemoglobin and the rate of the feeding GDA.Results The molar ratio of GDA to hemoglobin is the most important influencing factor on the molecular weight distribution of polymerized hemoglobin,followed by the mass concentration of hemoglobin and the rate of feeding GDA.When analyzing the impact on the mean molecular weight,there were significant differences between mean molecular weight corresponding to different molar ratios of GDA to hemoglobin (P＜0.05),while there was no statistical significance between mean molecular weight corresponding to different mass concentrations of hemoglobin and the rates of feeding GDA (P＞0.05).When analyzing the impact on the effective conversion ratio,there were significant differences between effective conversion ratios corresponding to different molar ratios of GDA to hemoglobin and different mass concentrations of hemoglobin (P＜0.05),while there were no statistical significances between effective conversion ratios corresponding to different rates of feeding GDA (P＞0.05).When analyzing the impact on the content of super-weight molecular,there were significant differences between content of super-weight molecular corresponding to different molar ratios of GDA to hemoglobin,while there were no statistical significances between content of super-weight molecular corresponding to different mass concentrations of hemoglobin and different rates of feeding GDA.Conclusions The optimal matching conditions of hemoglobin polymerization process were determined by orthogonal designs.