Unmanned aerial vehicles (UAVs) are used in aerial photogrammetry and digital low-altitude remote sensing, which has the characteristics of low operating cost, high efficiency and flexibility, and a wide range of applications. The fuselage and main wing with better drag reduction, weight loss and strength increase were selected, the motor and propeller with the optimal ratio in the ascending, takeoff and cruising segments under the same power condition were calculated, and the metal steering gear with higher power and safety was preferred as the servo. The electronic governor, landing gear, flight control, image transmitter, ground receiver and other components were carefully selected. So the optimized modular low-altitude long-endurance UAV was integrated. In order to reduce the weight of the flight platform, increase the load, extend the flight time and distance, a large number of repeated experiments were carried out to select the type, and various basic functions were tested. Compared with the traditional flight platform, the UAV flight platform has the characteristics of long flight time and long flight distance. It can also be equipped with more equipment such as miniature SLR, downhanging release cabin, weather detector, etc. The taken photos can be easily uploaded with the satellite link, and it can be modeled with one click when connected with the ground station. The UAV can take off by hand and land at various venues, support additional accessories for ejection, taxiing, vertical take-off and landing, and can slide down and parachute. It has broad application prospects in emergency earthquake relief, land and resources survey and monitoring, digital city and major engineering construction, etc.