The invention relates to an underground flow collection type ultrasonic wave Doppler flow-moisture content meter. The problem that the fluid flow cannot be measured by the existing flowmeter under two phase and three phase conditions is mainly solved. The underground flow collection type ultrasonic wave Doppler flow-moisture content meter is characterized in that an ultrasonic probe (1) is mounted on the upper end of a liquid outlet (4); the end faces of the ultrasonic probe (1) are respectively a receiving face (2) and an emitting face (3); the axial included angle a between the emitting face and the ultrasonic probe (1) is 70 degrees and 80 degrees; the axial included angle b between the receiving face and the ultrasonic probe (1) is 80 degrees and 90 degrees. The underground flow collection type ultrasonic wave Doppler flow-moisture content meter is capable of measuring the fluid flow under the two phase and three phase conditions.