The closed forging die structure of inserting upper die into lower die is not applicable for extrusion form of value bodies because of hollow pieces with side heaves. A dissertation was made on the extrusion process for hollow pieces with side heaves，a new type of structure of closed extrusion dies for hollow pieces with side heaves and the main points of the die design were presented. The die adopted a closing structure with heel block locking the upper concave with lower concave，the forging forming within a closed cavity formed by two punches and two concave dies. The forgings without any flash can be produced with the new type of forging die.