The invention provides a radio frequency optical common-caliber composite target simulation device and method based on a dielectric transmission structure. The device comprises a radio frequency feedsource, a plano-convex dielectric lens, a dielectric prism, a light source and a collimating lens, wherein the radio frequency feed source is located on the focal point of the lens, the radio-frequency radiation emitted by the feed source is collimated by the dielectric lens to form a plane wave, and is transmitted to the working area through the triangular prism to be transmitted to and receivedby the antenna of an aircraft. Meanwhile, after an infrared target is collimated into parallel light, the reflection surface of the triangular prism is reflected to the entrance pupil of the optical lens of the aircraft. The optical axis of the reflected infrared parallel light coincides with the electric axis of the refracted radio frequency plane wave, so that the common-caliber composite of thetwo is achieved. The defect of the reflection type composite target simulation device is overcome. The device is simple in structure and high in integration degree.