Abstract: On the basis of the mean air temperature, precipitation, sunshine duration and evaportranspiration from 23 meteorological stations in the upper Yellow River basin from 1960 to 2001, the feasibility of using hypothesis test techniques to identify the long-term trend for major climatic variables has been investigated. Parametric test were limited by the assumptions such as the normality and constant variance of the error terms. Nonparametric tests did not have these additional assumptions and were better adapted to the trend test for hydro meteorological time series. The possible trends of annual and monthly climatic time series are detected by using a non-parametric method and the jumps have been examined in terms of 5 -year moving averaged seasonal and annual series by using moving t-test (MTT) method, Yamamoto method and Mann-Kendall method. The results showed that the annual mean temperature has increased by 0.8 ℃ in the upper Yellow River basin during the last 42 years. The warmest center was located in the northern part of the basin. The nonlinear tendency for annual precipitation was negative during the same period. The declining center in annual precipitation was located in the eastern part and the center of the basin. The variation of annual precipitation in the upper Yellow River basin during the last 42 years exhibited an increasing tendency from 1972 to 1989 and a decreasing tendency from 1990 to 2001. The nonlinear tendency for annual sunshine duration and evaportranspiration were negative, too. They have decreased by 125.6 h and 161.3 mm during the last 42 years, respectively. The test for jumps by using MTT method shows that an abrupt warming occurred in the late 1980s. An abrupt change of the annual mean precipitation occurred in the mid 1980s and an abrupt change of the mean sunshine duration took place in the early 1980s. For the annual mean evaportranspiration, two abrupt changes took place in the 1980s and the early 1990s. The test results of the Yamamoto method show that the climate jumps are mostly occurred in the 1980s, and two acute jumps were tested for the spring evaportranspiration in 1981 and for the annual mean temperature in 1985. According to the Mann-Kendall method, the abrupt changes of the temperature mainly occurred in the 1990s, the evaportranspiration jumps mostly occurred in the 1960s, and the abrupt changes of the sunshine duration primary took place in the 1980s. Although the results obtained by using three methods are different, it is undoubted that jumps have indeed occurred in the past four decades. This may result from possible climate change or the effect from human activities. It should be pointed out that it is not easy to distinguish between jumps and monotonic trends and further studies are required to identify these trends more precisely. However, it is believed that the approaches presented in this study could be useful tools for further examining the impacts of climate change on hydrological processes.