By using phase-field method, we investigate the morphological evolution of three-phase eutectic transition and four-phase reaction in Mo-Si-Ti system through 2D and 3D simulations. For the eutectic transition, we explore the growth of lamellar pair (Ti(Mo)₅Si₃ and β(Mo,Si,Ti)) with different supersaturation in liquid as well as with different lamellar spacing. Via the analysis of their growth velocity, we clarify the underlying reason for the stable (straight growth) and metastable growth modes (oscillatory growth). For the four-phase reaction, we observe the remelting of Mo(Ti)₃Si phase and the formation of lamellar pair on the surface of Mo(Ti)₃Si phase. Different from the eutectic transformation, the lamellar pair grows with a certain orientation angle during this four-phase reaction. In addition, a comparison between the 2D and 3D simulation reveals the influence of the neighbor particle in the third dimension on the growth of the lamellar pair.