The invention discloses a cabin door structure of a passenger car, comprising a cabin door outer plate and a passenger car body which match with each other. The cabin door outer plate is fixedly connected with a section, the section comprises a rectangular tube, two mutually parallel side surfaces of the rectangular tube respectively extend along the same direction to form a long plate and a short plate, and both the long plate and the side surface, which extends out of the long plate, of the rectangular tube are fixedly connected with the cabin door outer plate. The strength of the cabin door outer plate is improved, distortion is reduced, and deformation of the cabin door outer plate due to the fact that the cabin door outer plate is repeatedly opened is avoided. Simultaneously, a sealing structure is optimized, waterproof and sealing performances of the cabin door of the passenger car are improved, and service requirements of the passenger car are met.