The invention discloses an on-site X-ray detection and three-dimensional imaging device of a GIS (Gas Insulated Switch). The on-site X-ray detection and three-dimensional imaging device comprises an X-ray machine (3) and an imaging plate (2). The on-site X-ray detection and three-dimensional imaging device is characterized by further comprising a circular orbit and a sliding device, wherein the sliding device is connected with the circular orbit and is capable of sliding along the circular orbit; the X-ray machine (3) and the imaging plate (2) are respectively arranged at two ends of the sliding device. The X-ray machine and the imaging plate can link along the circular orbit and can ensure that the window center of the X-ray machine is always aligned with the center of an effective imaging unit of the imaging plate, so that GIS equipment can be photographed from different angles, two-dimensonal images are reconstructed into three-dimensiona images, the GIS equipment is not needed to be fixed by workers for photegraphing during the process, the photographing effect and the detection efficiency are greatly improved, and the labor cost is lowered.