Abstract: This paper simulates the 3C crosswell seismic data of a common source gathered in VTI medias with the finite difference method,and identifies the quick P wave,the slow P wave,the quick S wave and the slow S wave in the crosswell seismic field.And it analyses the waves transmitting velocity and polarity,which can provide the guidance for wavefiled separation of crosswell seismic data,imaging of different waves and combining interpretation of the P wave,the S wave,the quick and the slow waves.