The technology of pre-stack time migration is selected to obtain accurate speed and migration imaging of steep dip structures with complicated surface conditions and severe variation of thickness and lateral velocity at Area A in the east part of Sichuan Basin. On the Basis of the pre-stack fine processing, the high precision of velocity field is set up and the offset parameter test is carried out. It is showed that this technology is characteristic of high precision migration imaging of pre-stack time, fine migration of the energy, and significant improvement in signal-to-noise and resolution ratio in target beds.