The present invention discloses an ultra wide band fixed phase shifter based on a capacitive load, which includes N physically separated phase shift units, and each phase shift unit includes an orthocoupler, first and second transmission lines, and first and second capacitive loads, wherein the orthocoupler includes an input end, a coupling end, a direct-connection end and an isolation end, one end of the first transmission line serves as a signal input end of the phase shift unit and the other end is connected with the input end of the orthocoupler, one end of the second transmission line serves as a signal output end of the phase shift unit and the other end is connected with the isolation end of the orthocoupler; one end of the first capacitive load is connected with the coupling end of the orthocoupler and the other end is grounded; one end of the second capacitive load is connected with the direct-connection end of the orthocoupler and the other end is grounded. The ultra wide band fixed phase shifter based on a capacitive load has compact structure, small area occupation and small insertion loss, does not need extra power supply and logical control, and can be widely applied.