Piezoelectric transducer is the basic components of acousto optic tunable filter (AOTF) with piezoelectric lithium niobate chip as the core component.The performance of the piezoelectric chip directly affects the performance of the AOTF.In this paper, the COMSOL Multiphysics software was used for finite element simulation analysis of the piezoelectric lithium niobate chip. Based on COMSOL Multiphysics piezoelectric module, transient analysis was carried out on ultrasonic piezoelectric transducer made of lithium niobate chip. Displacement of piezoelectric lithium niobate chip changing with the time was gained by transient analysis.