Abstract: Based on the observational data of the Lancang River flow from January 1995 to Decembe 2001,the correlation and multi-timescale characteristics of the monthly variations for Lancang River flow in the region of Yunnan are investigated.With the correlation analysis and wavelet transform,the results show that over the lower reach Lancang of River flow’s are influenced by the upper reach fo Lancang River flow’s variations,and the climate changes over Yunnan.The monthly variations for Lancang River flow in the region of Yunnan obviously appear multi-timescale features.There might be 4 and 53 months’ characteristic timescales of the monthly climate changes over the regions of the upper and lower reaches Lancang River.The 7,30 and 74 months’ characteristic timescales of Yinjinghong are due to the flow’s variations of Jiuzhou,but the 14 and 21 months’ characteristic timescales of Yinjinghong are due to the monthly climate changes over Yunnan.Corresponding to the smaller characteristic timescale,the time phases of the flow’s variations influenced by the monthly climate changes over Yunnan equal or lag the time phases of the upper reaches Lancang River flow’s variations.For the larger characteristic timescale,the time phases of the flow’s variations influenced by the monthly climate changes over Yunnan always lag the time phases of the upper reaches Lancang River flow’s variations.