Pressure adjustable casting method and crucible therefor

A pressure-adjustable casting method includes such steps as putting casting mould and molten metal respectively in upper sealed chamber and crucible, vacuumizing them, filling inertial gas or compressed air in the crucible, pressing the molten metal in mould cavity along the flow-up tube under the action of adjustable pressure difference, vacuumizing the vacuum hood while adjusting the pressure in crucible to quickly change it from negative pressure to positive one, solidifying the cast workpiece, and releasing the pressure. Said crucible for adjusting pressure is composed of crucible body, water cooling flange, and pressure adjusting pipe interface.