Abstract: Base on beamlet's local dualism in both wavefield decomposition and space propagation, use the Fourier propagate operator to complete the propagation of the beamlet, combine the imaging conditions to gain the imaging value and then imaging.To testify the theory, first construct beamlet and the beam source record, then apply it to pre-stack depth migration numerical experimentation, the outcome is inspiring. It also testified that the beamlet pre-stack migration is both effective and efficient.