Anti-submarine operation is a world-class difficult problem,in which finding submarines in time is acritical step. The underwater early warning system is a means with high efficiency and strong concealment in detecting and searching submarines. A new type of underwater monitor is proposed to solve the problems of underwater early warning system,which are insufficient detection performance,high cost and inconvenient deployment. A new underwater monitor is conceived,with its detecting and searching mode designed,specifications discussed,and key technologies and feasibility analyzed.