An inertial impact linear piezoelectric motor based on cantilever beam was designed to meet the requirements of optical fiber scanning and positioning during the observation of large sky area multi-target fiber spectroscopic telescope (LAMOST).The driving mechanism of the motor was also investigated.In order to avoid resonance, the first order resonance frequency of the vibrator was obtained by finite element simulation.The prototype motor was designed and fabricated, and an experimental platform was set up to validate the working principle and evaluate the performance of the motor.The results show that when the preload was 0.2 N and the driving signal was half of the sawtooth wave offset, the voltage peak-to-peak value was 60 V(600 Hz),the no-load velocity of the prototype motor reached 1.83 mm/s. The displacement resolution of the motor was 0.8 μm when the driving voltage peak-to-peak value was 15 V.The maximum load of 0.18 N and stroke of 40.5 mm were obtained under the driving signal peak-to-peak value of 60 V(600 Hz) and the preload of 0.4 N. The performance parameters of the motor meet the requirements of LAMOST′s fiber positioner scanning.