The physics process of γ-detection of γ-spcctrometer with Compton suppression shields has been simulated using Monte-Carlo method. The results calculated for the γ-source ¹³⁷Cs with energy of 662 keV and for the cascade γ-source ⁶⁰Co with energies of 1173 keV and 1332 keV were in agreement with measurements. This work should be useful in the physics design, for γ-spectrometers with Compton suppression shields.