Abstract: The total process of hydraulic transient for products batch transportation is simulated with the multistep MOC method.During the simulation, the movement of batching interface is considered, and the variation of fluid density, wave velocity of disturbance flow and friction drag factor within the pipe which are caused by the movement.The calculation result of the simulation is basically in accordance with the test record of batch transportation.What the paper puts forward is that the exactly most of the time for contaminated product flowing within the pipe can be described with the rigid water column theory, beyond the hydraulic transient caused by the contaminated product flowing through the intermediate station must be described with the elastic water column theory; and at the same time it is pointed out that the duration of hydraulic transient caused by the switching over of the initial station is about equal to the two times of going and back of surge wave; the maximum duration of hydraulic transient caused by the intermediate station is equal to the time of the contaminated product flowing through the station and the duration of hydraulic transient caused by the product switching over of the intermediate station.