Objective To measure and compare the normal values of blood routine examination in conventional,SPF SD and Wistar rats.Methods Hitachi-7150 was used in this experiment. Results The ALT,ALB,ALP,BUN,CRE,Fe,P,Mg,UA,LDL,PBA in conventional and SPF SD rats had very significant difference (P<0.01).The TP,ALB,ALP,CHO,TG,BUN,LDH,P,Mg,UA,HDL, PBA in conventional and SPF Wistar rats had very significant difference(P<0.01),the LDL had significant difference(P<0.05),the ALT,ABG,CRE,Fe,GLU,GOT had little difference(P>0.05). Conclusion Different microbiological background significantly affects the biochemical values of rats.