Free-growth morphology of crystalline grains was firstly observed within the cavities of titanium silicon carbide (Ti3SiC2) ceramic prepared by in-situ FE-action of polycarbosilane (PCS) and metal titanium. The pores produced by pyrolysis of PCS in Ti3SiC2 Ceramic can offer space for free growth of Ti3SiC2 and the liquid of CaF2 additive promoted the formation of Ti3SiC2 within such cavity. The perfect two-dimensional morphology reflects the growth of Ti3SiC2 single crystals. The growth mechanism of concentric layers on the {001} face was proposed. Berg's effect on the step movement was put forward and analyzed. From the view of the process of the movement of growth units, the reasons of stability and why it could be destroyed were discussed. (C) 2008 Elsevier B.V. All rights reserved.