The utility model belongs to the technical field of combine field output detects, concretely relates to combine cereal flow detection device, detection device install in harvester lift conveyer exit, and the mainly used harvester carries out real -time detection to the cereal flow when the farm work. This device mainly by the PVDF piezoelectric membrane, accept board, alignment jig, mount, charge amplifier, collection module and constitute. In the time of on cereal strikes the PVDF piezoelectric membrane, make the two poles of the earth of PVDF piezoelectric membrane produce the electric charge. Charge amplifier enlargies this kind of electric charge and exports with standard voltage. Collection module gathers the voltage of charge amplifier output in real time, obtains cereal flow value through the switch processing to export the result with the digital communication mode. The utility model discloses measurement accuracy is high, and anti -interference energy is strong, has realized the real -time detection to the cereal flow.