The invention discloses an automatic punching forming assembling device and method for door hinges. The automatic punching forming assembling device mainly comprises a feed mechanism, a punching mechanism, a conveying device and a riveting device. The feed mechanism, the punching mechanism, the conveying device and the riveting device are sequentially arranged from front to back. The punching mechanism comprises multiple punching machines sequentially arranged from front to back. Mechanism arms are arranged between the feed mechanism and the adjacent punching machine, between every two adjacent punching machines, between the conveying device and the adjacent punching machine and between the conveying device and the riveting device correspondingly. The feed mechanism comprises a feed frame. A feed working table assembly is arranged on the feed frame in a sliding manner. A material taking mechanical arm is arranged on the portion, above the feed working table assembly, on the feed frame in a sliding manner. A correction table is arranged on the side face of the feed frame. A vertically-arranged lifting hydraulic cylinder is arranged below the feed working table assembly and is connected with a cross-shaped top plate. The riveting device comprises a riveting working table. A riveting machine and a riveting clamp arranged in a sliding manner are arranged on the riveting working table. One end of the riveting clamp is connected with a push-pull oil cylinder. A hinge pin pressing oil cylinder and a guide cylinder which are oppositely arranged are arranged on the two sides of the riveting clamp. A stop assembly is arranged at the position opposite to the riveting machine.