Archival data of monthly air temperature and precipitation series were used to investigate climate change trends and characteristics during 1960–2000 at 19 stations along Lancang River from the north to the south, in the mountainous Himalayan region of southwest China. The magnitude of a trend was estimated using Sen's Nonparametric Estimator of Slope approach. The station significance of a trend was assessed by the MK test. Over the observation period of 41 years, mean annual air temperature increased at the rate of 0.01°C/yr to 0.04°C/yr in 12 stations at the significance level α = 0.01. The changes in precipitation in different areas are very dissimilar and complex. Mean annual precipitation that decreased from −2.86mm/yr to −5.29mm/yr at 3 stations, and mean annual precipitation that increased from 5.77mm/yr and 7.44mm/yr at 2 stations, were statistically significant at the significance level α = 0.05. The lower reaches of Lancang River experienced much more severe temperature increase, precipitation decrease, and drought development than the upper reaches in the past 41 years.