With the continuous updating of the relevant regulations of the Civil Aviation Administration and the imminent commercial operation of the domestic C919,it is of great significance to establish a domestic flight plan sys-tem that can adapt to the changes in regulations and independently control key technologies.First of all,the core con-cept of extended range operation(ETOPS)and its flight plan production process are summarized.Then,the iterative method is used to solve the windless equal-time point,and the linear interpolation method is used to calculate the wind and temperature at a specific time and space point,so as to obtain the key information of the ETOPS flight plan such as the equal-time point,the diversion fuel,the diversion distance,and the fuel critical point.Finally,a flight from Xiamen to London is taken as an example.The research results show that the ETOPS flight plan-making process and solving algorithm are of high accuracy,and the flight plan-making program written using Python software is feasi-ble,which can provide a reference for the development of domestic flight plan systems.