Abstract: Gansu zokor (Myospalax cansus) is a solitary fossorial rodent inhabiting in its own tunnel system all its life.In this paper,the sex ratio in wild population of Gansu zokor,the variation of sex ratio among seasons,years and age groups,and the relationship between the sex ratio and the environment factors were studied.The result showed:1) the sex ratio in wild population of Gansu zokor was 1.57 (♀/♂) (χ2=47.6,P<0.01);2) sex ratio changed among seasons and age groups;3) sex ratio also changed among years,but not significantly;4) in breeding season (April to August),sex ratio was correlated with the amount of precipitation (in the months with a precipitation less than 5 mm or more than 40 mm,the amount of precipitation of these months was significant correlated negatively with the sex ratio in next month (r=-0.764,P<0.01);5) the sex ratio did not related to the temperature.