The invention discloses a machining method for a welding groove of a non-centripetal connecting pipe and a barrel body of a pressure container. The machining method comprises the steps that the barrel body is drawn at first, an open hole is drawn in the barrel body, and then an open hole lofting line and an initial centripetal hole lofting line are drawn; and then the welding groove is machined by utilizing a barrel body outer side lofting graph and a barrel body inner side lofting graph. According to the provided machining method for the welding groove of the non-centripetal connecting pipe and the barrel body of the pressure container, the accuracy of the gas cutting groove can be effectively ensured, the effect that the root of the groove cannot be damaged by the gas cutting open hole is ensured, welding deformation can further be effectively controlled, and the post-welding size of the connecting pipe is ensured.