Abstract: Home ranges of root vole ( Microtus oeconomus ) in a brush community (Dasiphora fruticosa) on Qinghai plateau ( about 3200 m. above sea level) were estimated by mark and release trapping from May to October of 1980. The material collected consisted of a total of 1705 captures of 303 individuals.Home ranges were calcuated by several different ways on the same material: inclusive boundary strip method ( Stickel, 1954 ) , circular ( Calho-un and Casby,1958 ) and elliptical home range or principle component methods ( Jennrich and Turner, 1969; Mazurkiewicz, 1971) and mean's method ( 村上,1971 ) .The mean's method and principle component method are preferable. In order to simplify the procedures of calculation, we proposed a simplified mean's method and its results are considered quite near to that from the proper mean's method.Home ranges of male adults are larger than those of females. The male adults have their largest home ranges in May and June due to reproductive activity bur in September their area decreases to minimum. On the other hand, the females have their smallest home ranges when they are in pregnant or at nurse, and after reproductive period the home ranges increase to maximum in September. Home ranges of juveniles are smaller than those of adults, In most cases, the shapes of home range are elliptical and the mean ratio of axes of elliptical ranges calculated from principle component method is 2.48, but in the population there are about 15% of individuals with slender home ranges or with a linear capture points ( in this case the area of home ranges is not able to be estimated by principle component method)。Overlap of home ranges usually not occur in female adults in reproductive period, but they are often overlapped each other in the male adults in the same period.