During the construction of cutter suction dredgers loading barge,operators frequently adjust the speed of underwater mud pump motor to stabilize the mud flow rate in pipeline.To solve this problem,the automatic speed control system of underwater mud pump motor is designed by using fuzzy -PID technology.The control method takes velocity as the independent variable,mud pump speed as the dependent variable,and suction vacuum,mud pump power and mud density as the security conditions,so as to ensure that mud velocity can be kept within the set range during barge process.Practical application shows that the fuzzy-PID control has the characteristics of fast response,accurate control and good robustness in the process of underwater mud pump speed regulation,which has good promotion value.