The invention relates to a high-working-ratio nano material cold cathode electron gun, which comprises a focusing electrode, an anode, a cathode, a shadow grid and a control grid, the shadow grid is arranged on a cold cathode emission surface, the shadow grid and the cold cathode emission surface are in an equipotential state, and the shadow grid is prepared from a metal material or a semiconductor material; and the control grid is arranged right in front of the shadow grid at a preset distance, the shape of the control grid is similar to that of the shadow grid, and the shadow grid and the control grid are arranged opposite to each other and are arranged opposite to the cathode emission surface. According to the cold cathode electron gun adopting the technical scheme, electron bombardmentof the control grid is avoided, the problem that the control grid is burnt is solved, the problem that the cold cathode electron gun only can work in a small working ratio state is solved, the application of a nano material cold cathode electron gun in an electric vacuum device is expanded, and even development of rapid starting of an electronic system is promoted The cold cathode electron gun has the characteristics of simple structure and convenience in assembly.