Solar-powered UAV theoretically have the ability to fly continuously in the atmosphere, but there are huge challenges. Previous research focuses on the design phase, and puts forward optimization design methods, control methods and flight strategies. This paper focuses on how to carry out the continuous flight of the fixed solar-powered UAV. In this paper, a calculation model of continuous flight is built, which is composed of solar radiation calculation model and battery weight calculation method. The main factors such as latitude, flight profile, equipment power, solar panel efficiency and battery performance are analyzed. The results show that latitude and flight profile can improve the mission performance of solar aircraft, and the efficiency of solar panel is not as good as that of battery.