Microstructure and mechanical properties prediction technology has been developed for few years.Its main applications include optimizing processing parameters for improving mechanical properties,reducing scatter of mechanical properties and assisting developing new grade steel.In present paper,mathematical models originally developed on conventional hot rolling line for describing austenite evolution during rolling and cooling process have been applied on CSP line.The applications include three aspects : ( 1) upgrading 345 MPa grade C-Mn steel to 420 MPa grade or even higher strength steel,(2) optimizing laminar cooling processes to produce economical C-Si-Mn DP ( dual phase) steel and ( 3 ) designing the optimal rolling schedule for improving microstructure homogeneity of Nb containing steel.