According to the prediction requirement of the measurement of fission product samples before and after the gas-solid separation,a simulation method for γ-ray spectrum measurement was established. With the way of modifying the independent yield database,all fission product activities before and after the gas-solid separation could be calculated. A universal calculation formula for the γ-ray peak areas was also deduced on the basic principle of gamma measurement by HPGe detector. Combining with above work,a s...