The invention discloses a pressure injection mold for a pulley on a hydraulic machine. The pressure injection mold comprises a power mechanism and a molding mechanism. The power mechanism comprises a fixing plate and a pressing column. A feeding chamber is arranged in the fixing plate. The pressing column is connected with the feeding chamber in a sliding manner. The molding mechanism comprises an upper mold plate, a lower mold plate and a supporting plate. The upper mold plate is internally provided with a feeding port and bent pins arranged symmetric about the center line of the upper mold plate. A male mold and a core are arranged in the lower mold plate. The core penetrates the male mold to abut against the feeding port. The supporting plate is arranged below the lower mold plate. A locking mechanism is arranged between the upper mold plate and the lower mold plate. The fixing plate is fixedly connected with the upper mold plate. The bent pins are connected with both the locking mechanism and the lower mold plate in a sliding manner. The feeding chamber is communicated with the feeding port. A molding cavity is defined by the pressing column, the upper mold plate, the locking mechanism, the male mold and the core. By the adoption of the scheme, the problems that an existing pulley mold is high in production cost and low in production efficiency are solved.