Simulation calculation were performed by using a more realistic nuclear model (a Fermi-type distribution of the nucleon density).In the calculations，a broken line was used for approximate treatment instead of the curve trajectory of the particle motion，the refraction and ref1ection of the particles at the nuc1ear surface also were considered. The free nuc1eon cross section were used in determining the collisions within the nucleus，and the statistical sampling techniques were used throughout. The energy level of the incident particles was restricted to the limit below 350Mev，i.e. ，the energy range in which pion can't be likely produced. The elementary calculative results were compared with experimental data.