The invention relates to the technical field of sealing gasket stamping equipment, in particular to a stamping system for plate heat exchanger sealing gasket production and machining and a stamping method thereof. During pouring, an electric control telescopic rod is controlled to contract, namely, a connecting block moves upwards, on one hand, the connecting block is matched with a pouring assembly through a stamping assembly, a groove faces a pouring pipe, molten raw materials in the groove are injected into a pouring cavity from the pouring pipe, and at the moment, a torsional spring enables a blocking door to block the bottom of a pouring grooves, on the other hand, the connecting block drives the rotating assembly through a transmission assembly to enable an outer gear ring to rotate, so that the pouring area is changed, and complete pouring is achieved, during stamping, the electric control telescopic rod is controlled to extend, on the contrary, a first rack and a stamping ring move downwards, the stamping ring stretches into a pouring cavity and extrudes a sealing gasket, a blocking door is extruded by the upper portion to be automatically opened, and therefore the sealing gasket automatically falls off, and a rotating disc reversely deflects to enable the groove to face the material guide pipe again for next casting molding and stamping.