The main aim of seismic exploration is to correctly image the subsurface structure. Because the azimuth of data collection is not always normal or parallel to the structure trend, there are many difficulties in 3-D seismic processing especially 3-D pre-stack processing. A new imaging method-Radon projection 3-D pre-stack depth migration is presented to solve this problem, which extends the 3-D migration by Radon projection to pre-stack imaging. The full 3-D pre-stack data volume is projected onto a series of pre-stack radial lines, which are migrated with the common 2-D pre-stack depth migration. Then, the reverse projection on depth slice is applied to get the 3-D migrated volume. Real data example shows that this method can improve horizontal resolution of imaging sections and get better images for steep formations and small faults.