Impact tests were carried out on armor plates of different thickness with tungsten spheres of different diameter. By observation and analysis

deformation laws were obtained relating to critical penetration velocities. The test results showed that in all phases of velocity different deformations could be observed

and the deformation varied greatly with different penetration velocities. This paper points out that the deformation should not be neglected in the research of the penetrating of tungsten spheres into armor plates. The research about the deformation of tungsten spheres is of important practical value in engineering.