Objective To determine and compare the blood parameters and blood biochemical parameters in F1 and F2 germ-free rats． Methods Germ-free rats were obtained by uterectomy，and the offspring were fed with artificial milk by hand in the germfree isolator． The blood parameters and blood biochemical parameters were detected by automatic hematology analyzers． Results The germ-free rats showed significant differences in the values of RBC，HGB，HCT，MCV，MCHC，RDW，MPV，NE% ，LYM% ，EO% ，BA% ，NE#，LYM#，EO#，BA#( P ＜ 0． 05) and ALT，ALB，LDH，CHO，TBIL，HDL-C，LDL-C，GLO，GLU，ALP，A /G，UA，P(P ＜ 0. 05) ． There are different blood values in different gender and age．Conclusion The gender and age may affect the blood parameters and blood biochemical parameters．