The invention relates to a high reliability multifunctional welding machine clamping device. The device comprises a base, a fixed clamping table, a lifting and moving clamping table, two driving hydraulic cylinders, a centering mechanism, first and second pressure detecting members and a controller, and two guiding rods are arranged on the base; the fixed clamping table horizontally protrudes fromthe upper end of the front side of the base, a first groove is formed in the outer side of the upper end surface, and a front lining plate is embedded inside the first groove; a second groove is formed in the rear side of the upper end surface of the base, and a rear lining plate is embedded in the second groove; the lifting and moving clamping table is slidably disposed on two guiding rods; cylinder bodies of the two driving hydraulic cylinders are arranged on both sides of the lifting and moving clamping table, and the ends of piston rods are connected to the tops of the guiding rods; the centering mechanism is arranged in a guide groove of the lifting and moving clamping table; the first and second pressure detecting members are arranged under the front and rear lining plates; the driving hydraulic cylinders, a lifting hydraulic cylinder, a pressing hydraulic cylinder, a centering hydraulic cylinder, a displacement detector and the first and second pressure detecting members are all connected to the controller. The device overcomes the problems that an original welding machine is affected by the rubbing of a strip steel plate (edge waves, medium waves and the like) so that a strip steel cannot be effectively clamped, which affects the quality of a weld seam, and deviations easily occur to affect the welding reliability.