The invention discloses a processing method of an engine cylinder. A processing mechanism of the engine cylinder comprises a chassis, an angle adjusting unit, a clamping unit, a height adjusting unit,a boring power unit, an adjustable boring cutter unit and a heat treatment unit; the clamping unit is installed at the top of the chassis through the angle adjusting unit; four mounting plates are arranged on the side face of the chassis at equal angles; the boring power unit is installed on the installing plate on the left side through the height adjusting unit; the adjustable boring cutter unitis installed at the bottom of the boring power unit, and the heat treatment unit is installed on the installing plate on the rear side; and the heat treatment unit comprises a heat treatment equipment box, a baffle, an L-shaped door plate, equipment box legs, an electric push rod, a supporting rod, an end rod, a through hole, a door plate shaft, a push-pull block, a hinged support, a heat conduction circular plate, a circular blind groove and a heating wire. The production steps of the engine cylinder can be continuously carried out, the production coherence degree is improved, the productionefficiency is effectively improved, manual participation is reduced, and the labor cost is reduced.