The purpose of this paper is to provide a scientific basic for a unified standard for the reference value of middlescent people's erythrocyte sedimentation rate (ESR) in China. ESR measurements for healthy middlescent people were collected according to the Wintrobe method and the relationship between the reference value of middlescent people's ESR and altitude was tested in this paper It was found that the reference value of middlescent people's ESR decreases when the altitude gradually increases, and the relationship is quite significant. Univariate regression analysis was used to deduce two regression equations: Y1 = 13.14-0.00245X +/- 2.98 (males) and: Y2 = 22.00-0.00397X +/- 4.85 (females). If the altitude value of a particular area of China is known, the reference value of middlescent people's ESR can be calculated by means of these regression equations. Furthermore, depending on the altitude, China can be divided into three biogeographic districts: Qingzang District, Central District, and Eastern District.