Using electro-optic sampling technique and THz time-domain spectroscopy-transmission equipment, the reference THz wave and the sample THz wave has been measured from 0.3 THz to 3.0 THz and the absorption index has been obtained. Absorption peaks of β-Zn3BPO7 crystal sample were found in four points. The important condition of direct interaction between lattice and light is that they must have the same frequency and wave vector, also lattice vibration mode should be transverse because the light is electromagnetic wave. The absorption peaks are found multiple of the optical phonon basically after calculation. The sample shows great resonance absorption.