Abstract: The kinetics of work-hardened austenite transformation of TRIP(transformation induced plasticity) steel is different from the conventional C-Mn steel in their alloy contents, cooling rates and carbon contents in residual austenite, and all the differences should be emphasized for the TRIP steel. Based on the Avrami equation, the parameters of the kinetic model of phase transformation of hot-rolled Si-Mn TRIP steel were determined, and the influences of Si content, hot deformation and cooling rate on the phase transformation of hot deformed austenite were quantitatively investigated. The CCT curves predicted by the model showed that they are in good agreement with experimental ones. The calculation results show that the increase in either Si content or deformation benefits the ferrite transformation hence the carbon enrichment in residual austenite.