Abstract: The flow phenomena inside a slab casting mould are studied in detail.The different flow phenomena influenced by the operating parameters are discussed.For these purpose,a software for numerical solution of three-dimensional flow with microcomputer was developed.The new option for the wall function and method of pressure gradient order drop was deduced in the mathematical model.By comparing the results of calculation to that of measuring by LDA,it shows that the software is available,and it can be applied to predict the flow pattern inside the mould.