Objective To confirm the interference effect of heparin lithium on turbidimetry method for detecting total protein , and to conduct performance evaluation of it .Methods Eight different concentrations of total protein urine specimen with and with ‐out heparin lithium were detected respectively ,to confirm the interference of heparin lithium on the experiment .Adding different concentration of heparin lithium solution to the prepared total protein samples with concentration of 0 .172 ,0 .427 g/L(a series of interference experiment samples ,with heparin lithium concentrations of 0 .000 ,0 .025 ,0 .030 ,0 .035 ,0 .040 ,0 .045 ,0 .050 mg/L ) , repeat four times detection ,and then conduct the dose‐effect experiment of interference .Results The biggest bias of the testing re‐sults in the two paired samples was 159 .37% ,the mini‐bias was 11 .37% ,the difference of the results in two groups was statistical significant(t= 17 .24 ,P< 0 .05) .95% confidence interval of the interference effect in the total protein samples with concentration of 0 .172 g/L was 0 .034 ~ 0 .062 ,while in the total protein samples with concentration of 0 .427 g/L was 0 .043 - 0 .053 .When the heparin lithium were 0 .025 mg/mL and 0 .050 mg/mL respectively ,the results of bias of the total protein samples with concentra‐tion of 0 .172 g/L were 27 .33% ,58 .14% respectively .But in the 0 .427 g/L total protein samples ,the results of bias were 11 .24% 、18 .74% respectively .Dose effect of interference both showed a linear relationship in the series concentration of the hepa ‐rin lithium and interference of sample of 0 .172 g/L and 0 .427 g/L ,and the linear equations were Y = 1 .974X - 0 .001 03 ,Y = 1 .599 X - 0 .000 5 respectively .Conclusion Heparin lithium is the exogenous interfering substance to the detection of total protein in tur ‐bidimetry method ,it is the positive interference to the determination results of total proteins ,especially for the low level of total pro‐tein detection ,and as heparin lithium concentration increases ,the stronger the interference effect .