Oil well liquid level measuring method and device

The invention relates to an oil well liquid level measuring method and device for oil well liquid level measurement. The method includes the following steps that a, a ground frequency converter outputs frequency f1, the rotation speed n of a submersible screw pump is obtained through calculation, n is substituted into the formula of T3=91.3delta0-n0.45+46.5, and the torque T3(f1) of the submersible screw pump is obtained through calculation; b, the total power supply output torque T1(f1) is measured through a ground torque tester; c, the torque T2(f1) of lifting liquid is calculated through the formula of T2(f1)=T1(f1)-T3(f1); d, the height h(f1) of the lifting liquid is calculated through the formula in the specification. According to the measuring device, a power supply is connected with the submersible screw pump through a cable by means of the torque tester and the frequency converter. The measurement method and device do not depend on echo location and improve measurement precision.