Abstract: In order to reduce power consumption of underwater wireless sensor networks,this paper puts forward a wake-up signal detection algorithm on the basis of notch filter.The algorithm combines the principle of Parseval theorem and the sub-target detection algorithm.Through analysis of environmental noise,the detection threshold changes with the environment.This paper completes theoretical analysis and simulation of algorithm;applies it in micro-power processor;discusses the algorithm in underwater wireless sensor network applications.Test proved the effectiveness of the algorithm which can be flexible in scheduling states of each node in the network.The purpose of reducing the power consumption of sensor network is achieved.