Abstract: The existing commonly used hydrological methods for ecological flow calculation lacks consideration of the inter-annual natural hydrological rhythm.By dividing the incoming water period within a year and the incoming water year type between years, using the calculation principle of Minimum Monthly Average Runoff Method, two ecological flow calculation methods for natural runoff time-history allocation based on annual fixed inflow period(FPE)and different levels of years with variable inflow period(DPE)are proposed respectively in this paper.We also studied the temporal and spatial variation of ecological flow.The Wujiang River Basin is studied as a case.The results show that the ecological flow calculated by FPE and DPE are in a level that can be evaluated as 'good' by Tennant method.In terms of time history, the ecological flow calculation results in wet years show increasing trends, while the other year types show decreasing trends.Spatially, there is a significant positive correlation between the ecological flow of the control section of the river and the area of the basin.