The invention relates to a pressure pad device of a mechanical press. The pressure pad device comprises an ejector rod supporting plate on which an ejector rod is arranged; the pressure pad device also comprises a cylinder with a power source and a hydraulic cylinder without a power source, wherein both the cylinder and the hydraulic cylinder are fixedly connected with the ejector rod supporting plate, a rod-holding cavity and a rod-free cavity of the hydraulic cylinder are connected with an oil tank through oil pipes respectively, and a charging valve is connected in series to the oil pipes; and the rod-free cavity of the hydraulic cylinder is connected with a booster oil passage, and the rod-holding cavity of the hydraulic cylinder is connected with an unloading oil passage. The hydraulic cylinder is boosted by the booster oil passage after a sliding block descends to press the ejector rod, and is matched with the cylinder to achieve the rated pressure requirement, so that the cylinder does not need to be designed into a multistage cylinder with huge volume, meanwhile, the consumption of a gas source is reduced, and the use cost of a user is reduced; after the sliding block ascends, the unloading loop of the hydraulic cylinder is respectively locked, quickly unloaded and slowly unloaded according to the process requirements, and the ejector rod is fist static, then quickly ascends and slowly ascends when approaching an upper dead point, so that high impact and noise are reduced.