The metadata of 68 weather stations and the annual mean temperature series of 36 weather stations in Zhejiang Province are used to study the effect of observation environment variability on data homogeneity, and assessed by cumulative anomaly, boundary deviation and Ftest methods. The results show that from 1971 to 2004, the observation environment of the weather stations has changed d ramatically and the temperature temporal series of 39% stations were found heterogeneous, where the heterogeneity of about 36% stations are attributed to environment deterioration and that of about 57% stations to station relocation, which mainly occurred after the 1980s. The latitude and geographic environment differences before and after station relocation significantly influenced the homogeneity of temperature temporal series. More attention should be given to the effect of station relocation and environment variability.