Objective To make better use of CBA/ CaJ mice in biomedical research, the basic biological indicators of SPF CBA/ CaJ mice were determined. Methods CBA/ CaJ mice at six and twelve weeks of age were selected, and the main organ weights were detected. The blood physiological and biochemical parameters, and proportion of immune cells were measured using a full?automatic blood physiological and biochemical analyzer and flow cytometer, respectively. Results Compared with the male and female mice at the same age (6 or 12 weeks), body weight, heart, liver, kidney weight of males were significantly higher than females ( P < 0. 01). Mice with the same genders, the body weight of male mice at 12 weeks was significantly higher than the 6?week old male mice ( P =0. 000). Compared the male and female mice at six weeks, blood physiological parameters showed that MCV, RDW, PLT, P?LCR, BUN and CHOL of males were significantly higher than females ( P < 0. 01), while MCHC of male was significantly lower than female ( P =0. 000). Blood biochemical indexes showed that ALKP of male mice was lower than female at 12 weeks( P =0. 001), while CHOL was higher than female ( P = 0. 000). Mice with the same genders and different weeks, MCV, RDW, MCH and ALKP of 12?week old mice were significantly lower than six weeks ( P < 0. 01), while BUN was higher than six weeks mice ( P < 0. 01). The result of blood immune cell analysis showed that all mice had a certain proportion of B, T, NK cells and granulocytes. Conclusions The basic biological data of CBA/ CaJ mice are established. The result suggest that the cellular immune system for the CBA/ CaJ mice is intact, and these indicators are affected by age and gender.