This paper presents a new method of testing inhomogeneous broadening absorption properties of Tm3+:YAG crystal.Using the property of different absorbing energies at different frequencies,the inhomogeneous broadening absorption properties of the Tm3+:YAG crystal are obtained.We start from a harmonic oscillator model of particle at a single excited state.A theoretical model of the proposed method is also put forward.Experimental system uses linear chirped light as the source,and the change of ligh...