A simultaneous phase-shifting common-path interferometry with liquid crystal spatial light modulator (LC-SLM) is proposed for phase measurement of transparent sampl es.This method is based on the tri-window common-path interferometer which is built on a 4f o ptical imaging system, and a grating is displayed on the LC-SLM to act as a spectrum filter by the gra y modulation of the LC-SLM,thus,the phase of the sample can be obtained from three phase-shif ted interferograms which are recorded in one exposure.The mathematical model of the phase retrieva l is given;the performances of the proposed method and standard four-step phase-shifting meth od are compared by optical experiments,and the stability and repeatability of the proposed metho d are also evaluated by repeated tests.It is proved from the experimental results that the proposed method could achieve good performance in phase retrieval,and the stability and repeata bility could achieve 0.0325rad and 0.0732rad in stand ard deviation,respectively.