Abstract: The mechanism of intermixing is analyzed. Based on the incompressible, without regarding to the effect of buoyancy and the change with temperature of physical parameters, the intermixing model is developed. Numerical simulation for the concentration distribution of intermixing to batch pipeline is investigated with the help of PHOENICS software. The results are given by curves and pictures, and the result conforms to the values of diffusive theory well. The study is of significance to the intermixing investigation of batch pipeline.