Electrons traversing a transparent medium emit Cerenkov light when the electron velocity exceeds the velocity of light in the medium. A time-and-space resolved optical diagnosis system based on Cerenkov radiation for the uniformity of intense electron beam diode has been founded. Before the operation of a series experiments, Particle-in-cell and Monte Carlo simulation codes were utilized to design the experiment structure. The emission uniformity of two kinds of velvet sample was studied. It was found that the carbon velvet cathode has much bigger central enhancement zone and the Cerenkov radiation light of the area near the edge is also brighter. The operating state of diode can be obtained by analyzing the time evolutions of Cerenkov radiation light which achieves 10ns~100ns temporal resolution.