Abstract: In 1984,a nationwide survey on grain pesticide contamination was engaged in China.The main purpose of the survey is to estimate the average residues level and the percentages over the standard level of 666 （hexachloro-cyclohexane） and DDT （dichloro-diphenyl-trichloroethane） of various kinds of grain produced in 1983.A stratified two-stage sampling plan was designed for the survey using the provinces as strata,counties as primary units in each stratum and grain storehouses of townships （or communes） as subunits.Draw a sample of counties with probabilities （approximately） proportional to the grain production of counties without replacement and subunits with simple random sampling. The formulae for estimating the percentages over the standard level （or other characteristics） and their approximate variances are given for each province and the whole country using the stratified two-stage sampling with probability proportional to size with replacement.The results are compared with the accurate estimates according to the actual plan using Murthy’s estimate.