The rapidity is an important factor to the survivability of amphibious vehicles,which is also an important index to value the navigation performance of amphibious vehicles. In order to improve the run-ning speed of amphibious vehicles on water,wheels retracted and deployed were researched by resistance reduction. Then drag-reduction effect of wheel retracted was calculated and analyzed by numerical simula-tion. The results show that water-resistance is reduced when wheels retracted. Therefore,wheels retracted and deployed is an effective way to reduce the running resistance of amphibious vehicles on water. In gen-eral ,the study of this paper is a beneficial exploration to the design and performance analysis of high-speed amphibious vehicles,which lays the foundation for amphibious vehicles related technologies.