The utility model discloses a flat top is photovoltaic power generation for the building the integrated system of rainwater electricity generation belongs to energy power generation?sector. The utility model discloses synthesize power generation facility at least 3 of flat top building body top array arrangement, does this synthesize the photovoltaic power generation among the power generation facility does rainwater power generation facility fix on the supporting mechanism, photovoltaic power generation rainwater power generation facility utilizes the sunlight or collects the rainwater and generate electricity, and the electrical energy?storage who changes is in control system's battery, photovoltaic power generation the umbrella -type opens and shuts the mechanism and expandes to close the different generating electricity way of realization with receiving through the mechanism among the rainwater power generating device, the eaves is upwards protruding outside flat top building body's the roof, and messenger's roof rainwater is struck waters to take turns from building body water pipe midstream down stroke and is carried out hydroelectric power generation. The utility model discloses setting up power generation system on the roof, utilizing solar energy, rainwater to generate electricity, carry out electricity generation work at fine day and rainy day homoenergetic, improved the utilization ratio to the energy, the practicality is strong, convenient to popularize and use.