The utility model discloses a connecting device for sunshine plates. The connecting device comprises a fixed part, an installation part, a buckle and a fastener, wherein the installation part is arranged on the fixed part, the buckle is used for connecting adjacent sunshine plates, the fastener is arranged in the buckle, one end of the fastener is fixedly connected with the buckle, and the other end of the fastener is fixedly connected with the installation part. The utility model further discloses a composite sunshine plate. In a specific embodiment of the utility model, the fastener is arranged in the buckle, one end of the fastener is fixedly connected with the buckle, the other end of the fastener is fixedly connected with the installation part, so that the integral wind resistant capability of the sunshine plate is enhanced, and the problems of infirmness in installation, easiness in looseness at splicing seams and water leakage of the sunshine plate in the environment of higher wind pressure are effectively solved. The connecting device has the advantages of simple structure, rapidity in installation and convenience in maintenance and can be widely used for public buildings with sunshine plate roofings, such as stations, airports, superstores, exhibition centers and the like.