In this paper, based on MCNP5, the simulation model of profile gauge was established and verified by the experimental data. The inherent scattering of profile gauge was analyzed. The value of inherent scattering decreases with the increase of steel plate thickness. For the thickness of 1 mm to 15 mm, the inherent scattering accounts for less than 10% of the total scattering effect, and for over 15 mm thickness steel plate, inherent scattering can be approximated as zero. In addition, the analysis result of the bulge phenomenon for the scatter-to-primary ratio （SPR） curve proves that the detector stent can prevent another detector row＇s scattering.