Objective To study the quality control of urinary arsenic detection .Methods Quality control before ,during and after analysis were performed to avoid the random error and control the system errors .Results The low detection value of self-made quality control material of urinary arsenic and coefficient of variation (CV) were (0 .644 ± 0 .024) mg/L and 3 .72% ,respectively , while the high detection value and CV were (1 .353 ± 0 .042) mg/L and 3 .14% ,respectively .Conclusion Quality control before , during and after analysis may effectively reduce the incidence of random error and control the system error of urinary arsenic detec-tion and ensure the accuracy of test results .