The invention relates to a die mechanism with a side mold core and a sliding seat installed in a fixing die and an angle pin installed in a moving die. The die mechanism comprises the parts, such as a bolt, a guide post, a mold core, a mold insert, a supporting plate, a supporting block, a connecting push rod, a push plate, a main mold core, a fixing mold seat plate, a moving die plate, a locating screw rod, a mold core, a sprue bush, a concave die, the side mold core, a fixing die fixing plate, a spring locating pin, the angle pin, the sliding seat, a locking wedge, and the like showing the connecting mode in attached drawings of the specification). Two horizontal parting surfaces are designed for a die, wherein one parting surface is used for withdrawing a side loose core, and the other parting surface is used for taking out a product. The side mold core and the sliding seat are installed in the direction of the fixing die, and the angle pin is installed on one side of the moving die. Meanwhile, the main mold core is designed for the die to do delay action, thereby ensuring that the product is separated without remaining in the fixing die.