The invention discloses a flow rate measuring device based on an ultrasonic reflecting signal. The flow rate measuring device comprises a measuring rod, wherein a first probe with ultrasonic transmitting and receiving functions is arranged at the bottom end of the measuring rod; a first reflecting probe and a second reflecting probe are arranged around the first probe, and are connected with the measuring rod through connecting rods; the first probe, the first reflecting probe and the second reflecting probe are respectively connected with a signal processing unit. The flow rate measuring device based on the ultrasonic reflecting signal has the advantages that the plane two-dimensional flow rate is realized, the measuring blind area is small, and the like; a signal detection circuit only needs to detect the pulse reflecting time, a signal processing circuit is simple, and the instrument cost is greatly reduced in comparison with that of the ultrasonic Doppler measuring instrument.