AIM: To establish a set of statistic formulas on sampling error of infection rate of residents in sampling survey of schistosomiasis. METHODS: According to the requirement of multiple-stratifying and clustering random sampling, the sampling error of schistosome infection rate of residents was analysed through introducing the theory of error transferring and combining the calcu-lation formula of standard error in clustering random sampling and stratified random sampling. RESULTS: Four standard error formula of prevalence were introduced in different provinces and different types in endemic areas. CONCLUSION: The calculation formulas of multiple-stratifying and clustering random sampling are theoretically set up.