The invention discloses a rotating speed tracking method based on a permanent magnet synchronous motor open loop vector. The method comprises the following steps of 1, using a mixing model flux linkage observer to estimate a current motor rotor flux linkage angle, then carrying out differential and estimating a current motor rotating speed; 2, carrying out coordinate conversion on a stator currentvector and acquiring an excitation current id and a torque current iq; 3, taking the id and zero as input, carrying out operation by an excitation current regulator and acquiring an excitation voltage ud; taking the iq and the zero as the input, through a torque current regulator, acquiring a torque voltage uq; 4, carrying out vector synthesis on the ud and the uq, carrying out space vector modulation wave calculation, and comparing with a triangular wave to generate a driving control signal so as to drive a permanent magnet synchronous motor; and 5, repeating the steps1, 2, 3 and 4 till thattwo current vectors are stabilized near the zero and maintain for a short time period, considering the rotating speed estimated at this moment to be a current motor rotation speed, taking the currentrotation speed as a start rotation speed and smoothly switching to synchronization motor speed control.