In response to the problem that existing methods for calculating the basic instream ecological flow fail to balance the accuracy of calculated results and the simplicity of processes, a basic instream ecological flow calculation method integrating hydrological frequency, hydraulic conditions, and habitat requirements was proposed. With the natural runoff restored on the selected control section, the water use periods were classified according to hydrological characteristics of the river channel and water requirements of aquatic organisms, and the hydrological frequency arrangement was conducted for different periods. Then, the relationships between water discharge, mean water depth, and mean flow velocity were specified by the hydraulic method. Through analyzing requirements of biological environment indicators, including ecological water depth and ecological flow velocity, the basic instream ecological flow for different water use periods was determined. The proposed method was applied to the Shifeng River Basin in Zhejiang Province, and the results show that the calculated basic ecological flow of the representative section at the Shaduan hydrological station in the river basin was 16.0 m³/s during the spawning and larval development period and 4.4 m³/s during the general water use period. By comparison, the calculated results of the proposed method were in the range of those of the Tennant method, demonstrating the feasibility of the proposed method, and the values of basic instream ecological flow with higher accuracy can be obtained by the proposed method in different water use periods. Keywords: ecological flow; control section; hydrological frequency; hydraulic calculation; habitat requirement; Shifeng River Basin