Abstract: This is the summarization of a virtual cathode radiation experiment on the EPA-74 pulse-line accelerator. An electro-beam of current 1kA and energy 400kV is focused to form a virtual cathode by a short magnetic lens. The wavelength of the generated microwave radiation is between 6.2mm-11.5mm. And the peak output power is about 1MW. To enhance the emission efficiency, we are going to apply a deliberately designed experiment structure to form multi-stages virtual cathode.