The deoxidation system with a nonlinear structure is characterized by multi-input multi-output（MIMO）and great time delay.Its temperature and pressure are strongly coupled.For these reasons

it is hard to establish its precise mathematical model.The temperature and pressure must be kept steady to get rid of oxygen in water.But these requirements are almost unreachable when the ordinary PID control scheme is applied.A method of designing based on the fuzzy control theory is presented.At the same time

simulation of control system is also performed to study the performance of fuzzy control by Matlab

simulation result of fuzzy controller shows a very brilliant performance comparing to PID controller.