A regional average Spearman Rho method that takes into account both temporal and spatial correlation was developed. The method was used to assess regional variation trends of annual precipitation,annual mean air temperature,and annual potential evapotranspiration in each subcatchment in the upper Yangtze River based on the CRU dataset. The results show that the positive spatial cross-correlations between sites are prevalent for each climatic element. The annual mean air temperature and potential evapotranspiration also exhibit positive temporal autocorrelations. Both correlations can lead to overestimation of the significance of regional trends. If the correlations are ignored,it is concluded that a significant climatic variation occurs in each subcatchment in the upper Yangtze River. The new method effectively reduces the effect of temporal and spatial correlation,and concludes that the climatic trends have not been statistically significant over the last century,and that the annual precipitation only significantly increased in the Jinsha River area,whereas it slightly decreased in the Chuanjiang area. Meanwhile,the annual mean air temperature and potential evapotranspiration increased significantly after 1960. The results of the study indicate that consideration of temporal and spatial correlation plays an important role in decreasing trend misjudgment.