The invention discloses a microwave photonic frequency measurement device based on an electrooptical method Fabry_Perot cavity, and belong to the technical field of microwave photonic measurement. The device comprises a double-drive Mach-Zehnder modulator which is used for carrying out the inhibition carrier single-side band modulation of a to-be-measured signal through a modulation carrier; the electrooptical method Fabry_Perot cavity which is used for carrying out the tunable filtering processing of the signal after inhibition carrier single-side band modulation through the movement of a transmitted spectrum; a detector which is used for detecting the signal after the electrooptical method Fabry_Perot cavity carries out the tunable filtering processing, and determining the frequency of the to-be-detected microwave signal when the signal is detected. According to the embodiment of the invention, the device carries out the tunable filtering processing of the signal after the inhibition carrier single-side band modulation through the movement of the transmitted spectrum, can achieve the quick scanning of the signal, greatly shortens the signal detection time, and can achieve the measurement of the frequency of an ultrashort pulse signal.