A Monte Carlo code writen by C language for simulating the gamma-electron shower in material bas been realized on microcomputer. The programme can actively display the physical process of particle transport and reaction, and can accumulate various spectra selected by the user. The results are stored event by event on the disk and can be retreated afterward. The energy region available is 0.1 to 500MeV, but can easily be extended to lower or higher energies. The code could be used in the area such as gamma detection, protection of nuclear radiation and nuclear medicine.