In this paper, we mainly study the problem of electron cloud diffusion in high-speed ultraviolet photonic imaging detectors. In this paper, the size of the electron cloud transmitted by the microchannel plate and the anode in the high-speed ultraviolet photon imaging detector is studied by simulation, including the bias angle, pore diameter, voltage (U) and distance between MCP and anode (l) on the electron cloud received by the anode. the diffusion radius of the electron cloud increases with the increase of the bias angle, and the voltage (U) and the distance (l) between the MCP and the anode on the electron cloud received by the anode. The research shows that the diffusion radius of the electron cloud increases with the increase of the bias angle, the diffusion radius of the electron cloud. When U is larger, the energy of electron cloud is also higher. When the voltage increases to 1900V, the electron movement speed increases linearly with the increase of U. Moreover, the diffusion distance of the electron cloud radius increases with the increase of the transmission distance l. When the distance is 2 mm, a maximum electron diffusion radius is obtained. When the bias angle is 10°, the pore diameter is 10um, the voltage is 2000V, and the distance l is 0.5mm, the diffusion ratio of the electron cloud is 5.5. © 2023 SPIE.