Abstract: A rail apparatus, a laser apparatus, and a laser machining device are provided in the present disclosure. The rail apparatus includes a rail frame assembly and a mounting assembly. The rail frame assembly includes a rail frame and a guide shaft fixed to the rail frame. The mounting assembly includes a mounting base and a pulley. The pulley defines a sliding groove. The sliding groove is slidably connected with the guide shaft. The laser apparatus includes a base, a laser, and a focusing member. The laser is disposed on the base and is configured to emit a laser light. The focusing member is movably disposed on the base and has a focusing end. The laser apparatus is operable in a retracting state and an extending state. The laser machining device includes the rail apparatus and the laser apparatus.