Based on the inflow of the two biggest reservoirs in Fuhe river basin，this study used Copula function and analyzed the wetness-dryness encountering of Liaofang and Hongmen reservoirs.The results show the characteristics of the two reservoirs are similar in the period of the full year，flood season and non-flood season，and the synchronous frequency is much higher than the asynchronous frequency.The synchronous frequency of normal flow is the highest，and high flow year is the lowest.The synchronous frequency of low flow year is highest in the period of non-flood season，so more attention shall be paid to the synchronization of the wetness-dryness encountering in dry season.This study can provide some decision basis for multi-reservoir optimal operation in Fuhe river basin.