GYL-20300 series of unbalanced pressure relief control valve with double valve core, guide sleeve, designed for high temperature and high pressure difference and the leakage level demanding operating conditions design, make up the sleeve valve seat leakage volume, and not high temperature resistant single seat valve sleeve. The use of flow structure, through the use of the pressure generated by the medium pressure on the heart of the valve, a small thrust to open a small valve to move to a certain position after the exchange pressure and then drive the flow of large valve core adjustment or switch.