A simulation system based on personal computer in DOS environment has been designed to simulate the γ- ray measurement spectrum. The γ- ray spectra for reactor neutron activation analyses and the spectra of radionuclides can be simulated in this system on the basis of modeling for an experimental spectrum of 137Cs. In the spectrum

the photopeak

Compton edge

Compton plateau and backscattering peak are simulated. This system has functions of peak area calculating

spectrum shaping

spectrum displaying

spectrum processing and spectrum saving

etc. Using this simulation system

the γ- ray spectra of 137Cs

60Co

152Eu and the spectra of Zr sample

rock standard sample for reactor neutron activation analyses have been simulated. The simulation spectra are similar to the spectra measured in the actual experiment to a great extent.