The problem of multiple autonomous underwater vehicles (AUVs) cooperative target hunting is an important research topic for its potential applications, including military and civil. This paper proposes a method based on formation control to improve the efficiency and accuracy of target hunting. Firstly, AUVs run together to search the target in a large area where the target probably exists. At this stage, an improved leader-follower formation control algorithm is used to gather AUVs with the desired formation. Then after the recognition of the target, a route is planned for the pursuing of the target, and a formation control method based on the position feedback is presented to close and round up the target gradually. Finally, AUVs have the capacity to catch it. There is a standard set up to calculate the error of the formation control quantitatively. The field performance proves that AUVs can keep an expected formation well based on the formation control method to solve the problem of target hunting.