Due to the existence of power and thermal energy in regional integrated energy system, it is difficult to couple and analyze multiple energy flows. A multi-energy flow calculation method of regional integrated energy system based on time series and coupling analysis is proposed. Firstly, the frequency modulation characteristics of the system are analyzed by using time series to obtain the operation frequency of the system. Steady- state network model of regional integrated energy system is constructed. Secondly, power flow of power system and thermal system is calculated respectively and through electrothermal coupling analysis, multi-energy power flow calculation results of the system are obtained. Finally, experimental results show that this method can accurately calculate the heating temperature and regenerative temperature of different pipelines in the thermal system, and can also calculate the voltage, active power and reactive power during the operation of the power system, so as to realize a more comprehensive multi- energy power flow calculation.