Abstract: How to apply wireless sensor network to monitor the water environment has become an important subject. Based on the theory of square grid partition, this paper proposes a routing algorithm with the yardstick of entropy to evaluate the stability of route in the dynamic water environment. In this algorithm, the information collecting area is subdivided by means of cube grid, the shortest route to sink node in the grid is searched, and the router is chosen by means of entropy to reduce the number of reconstructing routers or repairing routers and possibly provide QoS guarantee in the environment in which network topology ration changes frequently. The stimulated experiment and performance analysis prove that EWSQoS algorithm takes more advantage than Long-term, DBR, and DTN algorithms in the fields of the number of reconstructing routers, success rates of routers, energy consumption of network, and network latency.