Objective To investigate the positive ratio of urine and gender difference of chronic kidney disease(CKD) with children in Lanzhou,a heavy pollution and underdeveloped city in northwest of China.Methods Through the Multistix 10 SG,the morning urine of the children were detected,which aged from 12 to 13 years old.Results The positive ratio of urine was 14.9% in subjects,18.2% in girls and 12.8 % in boys respectively.Furthermore,the positive ratio in girls showed statistically significant higher than boy's.(x2 =21.77,P < 0.01).Espcially,the ratios of hematuria and pyuria significantly increased in girls (x2 =17.52,P < 0.01;x2=7.95,P < 0.01).Conclusion The gender difference of the positive rate of urine was existed in our large samples.And there is a higher prositive rate of hematuria and pyuria in the girls.This investigation will enrich the epidemiological data of CKD in children(12 ~ 13 years old)in Lanzhou city.