The invention discloses a positioning device and a positioning method for effectively improving the strength of receiving signals of ultrasonic probes. The positioning device comprises a positioning device body and a control system, wherein the positioning device body comprises a pipeline, a first ultrasonic probe, a second ultrasonic probe, a sliding block, a track fixer, a stepping motor, a rack and a gear; the second ultrasonic probe is directly mounted on the pipeline; the first ultrasonic probe is mounted on the sliding block; the sliding block is mounted on the pipeline through the track fixer; the rack is arranged at the upper end of the sliding block; the stepping motor is mounted on the track fixer and is connected with the sliding block by the meshing of the gear and the rack; the control system is connected with the stepping motor, the first ultrasonic probe and the second ultrasonic probe. The device and the method are used for solving the problem that the receiving signals of the ultrasonic probes are weakened due to the fact that the propagation path of ultrasonic waves is changed along with the flow speed of a fluid, so that the strength of the receiving signals of the ultrasonic probes is effectively improved.