The invention discloses a fixing method of an engine exhaust manifold. The method comprises the following steps that A, fixing holes are formed in a workbench and distributed in the workbench in a matrix mode, two supporting plates I are mounted in the middle of the workbench at intervals and correspond to the shape of the middle of the exhaust manifold, a positioning plate is mounted between thetwo supporting plates I, a fixing annular buckle is mounted on the positioning plate, a fixing assembly for an exhaust manifold front fixing seat is mounted on the front portion of the workbench, anda supporting plate II for an exhaust manifold rear fixing seat is mounted on the rear portion of the workbench; and B, the exhaust manifold is arranged according to the front, middle end rear positions, the exhaust manifold front fixing seat is fixed through the fixing assembly on the front portion of the workbench, the middle of the exhaust manifold is supported through the two supporting platesI in the middle of the workbench and buckled tightly through the positioning plate and the fixing annular buckle, and the exhaust manifold rear fixing seat is supported and fixed through the supporting plate II on the rear portion of the workbench. By means of the fixing method, mounting is rapid, the welding efficiency is high, and application is convenient.