Objective To study the effect of age and sex on physiological and biochemical indexes of SJ5?SPF chickens at the age of different weeks. Methods Blood biochemical indexes of SJ5?SPF chickens at the age of different weeks were measured using an automatic blood analyzer, including 19 items: ALT, ALP, GGT, AST, LDH, TP, GLB, ALB, TB, DB, IBIL, GLU, TG, TCH, BUN, CRE, K+ , Na+ , and Ca2 + . At the same time, the body temperature (T), respiratory frequency (R), heart rate (HR), diastolic pressure (DBP) and systolic pressure (SBP) of the SJ5?SPF chickens were measured using a RM6240C multi?channel physiological signal acquisition and processing system. Results (1) Among the physiological parameters, the body temperature, respiratory rate, heart rate, diastolic blood pressure and systolic blood pressure showed significant differences between the 4?week old chickens and the chickens at ages of 20, 25, and 25 weeks ( P < 0.05), but there were significant differences between the males and females at the same weeks of age except body temperature. The diastolic blood pressure was only significantly different in the 40?week old male and female chickens ( P < 0.01). The heart rates showed significant differences between the male and female chickens at 4, 20 and 25 weeks of age ( P < 0.01). The respiratory rate and systolic blood pressure in the 4?week old male and female chickens were significantly different ( P < 0.05). (2) The 19 blood biochemical indexes showed significant differences between the male and female chickens: the GGT, ALT, AST, TB, DB, IBIL, GLU, BUN and Na+ at an week?age ( P < 0.05), the LDH, TP, GLB, ALB and CRE at two different week?ages ( P < 0.05), the ALP, TG and Ca2 + at three different week?ages ( P < 0.05), and the TCH and K+ at four different week?ages ( P < 0.05). Conclusions The above results can provide a scientific basis for diagnosis of SJ5?SPF chicken disease, animal quarantine and other related research.