Abstract: The therapy principle and design of microwave prostate hyperthermia are described. This apparatus uses 915MHz microwave treatment for the prostate. The solid state microwave source and surface cooling system of special design only heats the prostate. The specially designed Foley duct and microwave radiator can be used for treatment by transurethral or transrectal. The temperature is measured and monitered automatically, and the measured data are recorded, displayed and printed in real-time by a microcomputer. The accuracy of thermosensor measurements is 0.1℃.