The invention relates to a pressure welding method for large-area target which belongs to the welding field of metallic materials, and the method comprises the following steps that: (1) a roughening treatment is applied to the surface to be welded of the target; (2) the surface to be welded of a backplane is processed into a non-planar structure; (3) the surfaces to be welded of the target and backplane are washed and dried: (4) the backplane is heated and the preheated target or target at normal temperature is placed on the backplane and pressed, so as to deform the curved surface of the backplane till a bonding between two surfaces to be welded is achieved by pressing; (5) the target and the backplane are heated to the temperature which is 0.50 to 0.85 time of the melting point of one with lower melting point in the both and welded under the condition of heat insulation after being clamped tightly. The method has low processing requirement for the equipment and the surface to be welded and can ensure that no oxygen problem exists between the large-area target and the surface to be welded of the backplane, the air around the contacting surface between the target and the backplaneis completely discharged, firm bonding between the target and the backplane is realized in the atmosphere environment, simultaneously the microstructure performance of the target is not affected and problems of severe deformation, etc do not happen to the bonding surface between the target and the backplane.