Aiming at the influence of nuclear waste density on segmented gamma scanning (SGS) measurement, to study the influence on pulse count, put forward the Monte Carlo simulation method and establish the SGS system through Monte Carlo software MCNP based on the prototype, fill the waste barrel with two different density waste, and use the transmission source and mixed source to measure the energy spectrum respectively, contrast the simulation results. It shows that, the nuclide characteristic peak amplitude decreases with increasing the density, stray energy pulse amplitude increases with density increases, and the density change has a greater influence on the transmission measurement, it’s necessary to take density factor into account when correction calculation for specific correction.