The embodiment of the invention provides an inductance determination method and device for a permanent-magnet synchronous motor, which can measure the q-axis inductance and the d-axis inductance more accurately and improve the detection precision. The method comprises the following steps: obtaining the first rotating speed of the measured motor, which is controlled by a motor dynamometer to run; in the first rotating speed state, obtaining a first d-axis current, wherein the first d-axis current is the d-axis current obtained through the measurement when a motor controller controls the q-axis current of the measured motor to be zero, and the line voltage of the measured motor to be the first voltage; obtaining a second rotating speed; in the second rotating speed state, obtaining the second d-axis current, wherein the second d-axis current is the d-axis current obtained through measurement when the motor controller controls the q-axis current of the measured motor to be zero, and the line voltage of the measured motor to be the first voltage; according to the first rotating speed, the first d-axis current, the second rotating speed and the second d-axis current, calculating the first d-axis inductance of the measured motor; according to the first d-axis inductance, calculating the first q-axis inductance of the measured motor. The inductance determination method and device, provided the invention, can be applicable to the technical field of detection.