Abstract: In the paper, it was found that the counts of full-energy peak were significantly different from that dealing with nuclear radiation pulse by digital. The radiation of full energy deposition was tracked and simulated by particle tracking card in MCNP according to characteristic of detector. The simulated result indicates a few number of full energy deposition pulse shapes are similar to rising-edge pile-up pulse shapes. And true rising-edge pile-up pulse histograms are also given. The results provide well reference for digital dealing with rising-edge pile-up pulse and emendate the counts of full-energy peak.