The hydraulic metal baler extrudes the scrap iron,scrap aluminum,scrap copper,wire,sheet and other corner surplus into a specific shape of the mass to facilitate the recycling,transportation and reconstruction of the scrap metal.So pollution to natural environment caused by scrap metal is reduced as well as consumption to metal mineral resources.The research status of hydraulic metal balers at home and abroad in recent years was reviewed,the main problems of hydraulic metal balers in China were analyzed.The hydraulic metal balers process was introduced from three aspects:door locking method,pressing method and bag discharging method.The application of hydraulic system and PLC control system in hydraulic metal baler was summarized,and the development direction of hydraulic metal baler in the future was forecasted.