Abstract: Objective To understand the dietary diversity in residents of Wuhai, Inner Mongolia and to analyze its effect on serum lipid level. Methods Subjects were stratified by multi-stage sampling method from September to November in 2014 and 5 409 residents aged 18 to 79 years were enrolled in this study. Diet information was obtained by using food frequency questionnaire. Dietary diversity score (DDS) was calculated in order to understand the dietary diversity. The association between the dietary diversity and serum lipid level was analyzed by multiple linear regression. Results Mean dietary diversity score was 5.9±1.4 and the score of males was lower than that of females (t=-4.99, P<0.001). Education level and household income were positively associated with DDS (P<0.001). Subjects with high DDS consumed more vegetables, fruit, meat, egg, fish and soy (all P<0.05). Women with high DDS consumed less carbohydrate (Z=-2.84, P=0.005). DDS was negatively associated with total cholesterol (male, β=-0.040, P=0.028; female, β=-0.034, P=0.011) and low density lipoprotein cholesterol (male, β=-0.036, P=0.024; female, β=-0.032, P=0.006). Conclusions The dietary diversity of residents in Wuhai was poor. DDS was negatively associated with low density lipoprotein cholesterol and total cholesterol. We should increase the dietary diversity and the intake of fruit, milk and fish while decrease the intake of meat and refined carbohydrate.