Abstract: Abstract: Distributed photovoltaic power generation system is the fastest growing distributed power generation system in recent years. The advantages of flexible power generation, high energy efficiency and low environmental pollution make it become an important supplement to traditional power grids. The distributed photovoltaic power plants are mainly installed on various building roofs that need to be measured at the first place. The traditional survey method required manual climbing to measure roofs' structure and size, roof orientation, tilt angle, roof material, roof height and other parameters which was neither safe nor precise. Oblique photography technology is a new aerial survey technology developed in recent years. By carrying multiple sensors on the same flight platform, it can simultaneously capture images from different angles and simultaneously record flight height, speed, coordinates, etc, which can be used to quickly generate texture-rich real-life 3D models. Most of the Oblique photography systems were installed on air planes or fixed-wing drones which had high price and weight. In this research we developed a low-cost portable five-phase oblique camera ZTRS-M5B whose shell was made of lightweight aluminum alloy and designed with quick snaps for loading on all types of drone platforms. The oblique camera's size was 243 mm×243 mm×145 mm and weight was 1.8 kg. The camera automatically controlled the shooting of five Sony QX100s via the STM32F4 high-performance microcontroller and optocoupler and simultaneously recorded position and inertial navigation information using the embedded GNSS/INS system. The unmanned aerial vehicle (UAV) mapping system equipped with this oblique camera was used to measure a rural residential area and a factory area. The flight time in the residential area was 14 minutes in which the system took 1 052 images and the flight time in the factory area was 23 minutes in which the system took 1 755 images. All flight parameters were pre-set in DJI GS PRO ground control station which also controlled the UAV mapping system to complete the flight missions automatically. The captured images were pre-processed and imported into the Smart3D software for 3D reconstruction. By comparing with the ground measured values, the 3D reconstruction model's accuracy would be verified. The results showed that the model tilt angle of the photovoltaic power plant solar panel was highly correlated with the actual tilt angle, the average absolute error of the horizontal dimensional size of the building in the model of was 0.11 m and the average relative error was 0.37%, the average absolute error of the vertical dimensional size of the building in the model of was 0.12 m and the average relative error was 1.04%. This system could efficiently and accurately obtain the housing information needed for the construction of distributed photovoltaic power plants in the early stage, ensure the life safety of surveying staff and greatly reduce the cost of oblique photography survey. We also compared ZTRS-M5B's parameters with the traditional aerial oblique camera SWDC-5 and another small UAV oblique camera DM5-4200. It showed ZTRS-M5B had more advantage in the portability and dominated in the price although its image resolution was relative lower. This camera could take place other oblique camera in the market for the small and medium area surveying.