The invention discloses a welding method of an automobile generator exhaust manifold. The welding method comprises the following steps that a pedestal is firstly placed horizontally; a to-be-welded flange is placed on the side wall of a vertical plate, clamping rods are adjusted, press plates can tightly press the edge of the flange, and the flange is fixed to the vertical plate through nuts; a second drive mechanism is utilized for adjusting the height of the flange, and the welding face of the to-be-welded exhaust manifold is in contact with the flange; first drive mechanisms are utilized for adjusting the height of clamping strips, then moving rods are rotated, and the clamping strips can clamp the exhaust manifold; and the contact face of the flange and the contact face of the exhaust manifold are subjected to welding treatment. According to the welding method, the press plates on the vertical plate are firstly utilized for fixing the flange, then the position of the exhaust manifold is limited according to the fixed flange, then the clamping strips are utilized for fixing the exhaust manifold, and operation is simple and convenient.