Objective To understand the internal quality control(IQC)situation of routine biochemical projects in Guizhou Province from 2020 to 2022,and to use the analysis batch length sigma rule to select the appropriate IQC strategy for routine biochemical projects.Methods A sum of 41,41 and 52 laboratories were selected from the laboratories participating in the first external quality assessment(EQA)program of the routine biochemical project in the Guizhou Provincial Center for Clinical Laboratory from 2020 to 2022,which uniformly used two concentration levels of internal quality control products produced by Randox Company in the UK.The coefficient of variation(CV)was calculated based on their IQC information,and then these CV values were used to compare with imprecise performance specifications such as WS/T403-2012 standards.The IQC situation of routine biochemical projects of Guizhou Province in recent years was analyzed.Randomly 15 laboratories were selected each year to report the results of the triglyceride project,and their σ values were calculated.Based on the Westgard sigma rule flowcharts of the analysis batch length,appropriate quality control strategies were selected and the quality goal index(QGI)was calculated to evaluate analytical performance of laboratory detection system.Results In the current monthly CV,the proportion of laboratories that met the WS/T403-2012 standards for Ca and TP projects was relatively low,while the pass rates for 7 projects(P,CK,LDH and other projects)were all above 80%,showing an increasing trend year by year.The proportion of laboratories with the 7 projects(P,CK,LDH and other projects)meeting the performance specifications for biomedical variation(appropriate)all reached 90%,while the proportion of laboratories with 5 projects(Na,Ca,Cl and other projects)was relatively low.The proportion of 10 projects such as P,CK,and LDH in cumulative CV of laboratories that met the performance specifications for biomedical variation(appropriate)was over 90%.For the triglyceride project,from 2020 to 2022,there were 2,5 and 13 laboratories that reached 6 σ horizontal.Compared to values of 2020 and 2021 years,the trend of σ values changes of 2022 was increasing(t=3.855,3.511,P≤0.001),indicating that the analytical performance of these laboratories was getting better and better.Conclusion The IQC levels of routine biochemical projects in Guizhou Province were increasing year by year.The Westgard sigma rule of the analysis batch length is designed with personalized quality control rules for various laboratories in Guizhou Province,thus improving laboratory testing capabilities and better severing clinics.