The invention relates to the technical field of houses, discloses a rapid fabricated house and a mounting method. The problems that a large number of threaded nails are required to be used when a steel structure house is assembled and connected, consequently, mounting is inconvenient, a large amount of time is required to be spent in mounting, and meanwhile the steel structure house cannot be disassembled rapidly and conveniently are solved. The rapid fabricated house comprises a steel structure column and a steel structure beam, a U-shaped steel clamping piece is fixedly mounted on the upperportion of the steel structure column, a fixed inserting hole is formed in the position, located on the inner side of the U-shaped clamping piece, of the upper portion of the steel structure column, the end of the steel structure beam is movably connected in the U-shaped steel clamping piece in a clamped manner, grooves are formed in the two ends of the two sides of the steel structure beam, and afixed inserting piece is mounted at one end of each groove. The rapid fabricated house is assembled in a connection manner of clamped connection and inserted connection, meanwhile, the rapid fabricated house can be rapidly and conveniently disassembled in the connection manner of clamped connection and inserted connection, and therefore the house assembling and disassembling efficiency is effectively improved, and the house assembling and disassembling time is shortened.