Abstract: A relationship between fish conservation object and flow rate was developed using a concept model. In Jiaojiang River, fish was considered as the main conservation object in identifying the key components of environmental flow. Then environmental flow in two monitored sections was estimated via FLOWS method. In the Baozhiao section, the low, highest and full bank flows were 6.8~17.3 m³·s^-1, 22.2 m³·s^-1 and 948 m³·s^-1, respectively. Also the low and high flow pulses were 74 m³·s^-1 and 110 m³·s^-1, respectively. In the Linghai section, the low, high and full bank flows were 16.0~31.8 m³·s^-1, 46.0 m³·s^-1 and 2 488~3 184 m³·s^-1, respectively. The suitable environmental flow occurrence time, duration and frequency were also estimated. Compared with the Tennant method, the results from FLOWS method better reflected the seasonal characterizes of environmental flow in the river. The study also simulated the interconnection between environmental and natural flow. The findings therefore laid the theoretical basis for water resources utilization and fish conservation in Jiaojiang River.