Abstract: The scattering has serious influence on the image quality in X-ray CT.Multi-source CT is a trend of future CT system since it can significantly improve the temporal resolution.However, as the number of sources increases, more scattered radiation will occur.The scattering issue should be taken into consideration in the practical applications.A CT simulation software, SimProj, has been developed based on the open source tool EGSnrc to generate cone-beam projections which approach the real data.Reconstructed images from the simulated data show scattering induced artifacts as expected.The analysis results are important and helpful for the optimization of designing and manufacturing of triple-source cone-beam CT.