The invention discloses an electricity generation and water collection system installed on a roof. A sunshade and rainproof plate is installed at the upper end of a support in an inclined mode. A solar photovoltaic plate is laid on the surface of the sunshade and rainproof plate and connected with a power end of an electricity storage device through a wire. A water collection tank is arranged at the lower end of the sunshade and rainproof plate. A water guiding pipe is installed at one end of the water collection tank. The tail end of the water guiding pipe is communicated with a water inlet of a water storage pond. A water outlet of the water storage pond is communicated with an indoor power supply pipe net through a guiding pipe. The electricity generation and water collection system installed on the roof is simple in structure and convenient to install, and solar energy is absorbed through the solar photovoltaic plate to be converted into electric energy; the sunshade and rainproof plate replaces a traditional roof waterproof plate, and natural energy resources are beneficial to people's livelihood for mankind on the basis of modernization, standardization and integrated new urban and rural area house building.