The temperature, precipitation and runoff are the three key factors of meteorology and hydrology. It is of great importance to the development of agriculture and economy to analyze the characteristics of change and evolution rule of the three factors. Using time series data of the two national meteorology stations and two hydrology stations in the middle and upper reaches of the Meijiang River and combining some methods such as cumulative filter, Kendall's rank correlation and wavelet analysis to analyze the secular variation trend and the periodicity of meteorology and hydrology essential factor in this reach. The results show that：(1) The precipitation and runoff exhibit different degrees of reduction trend, but the temperature displays an obvious trend of escalation. The decreasing trend of runoff at the two hydrology stations and the increasing of temperature are extremely remarkable and pass the confidence level of 95% of the significant test; (2) The temperature, precipitation and runoff sequence of this reach have multi -time scales periodic variation, the annual average temperature of the main cycle is only 28a, the main cycles of precipitation are 28a,12a,7a and 4a, the main cycles of Jianshan station and Shuikou station are similar approximately, the former are 28a, 20a, 12a, 8a and 5a, the latter 29a, 20a, 12a, 9a and 5a; (3) On the other hand, the runoff at the two hydrology stations in this reach show significant decreasing trend in the case of rise in temperature and precipitation that remains almost unchanged, which is caused by human activities or climate change and should be studied further.