The preparation of ceramic tool materials includes powdering, forming, hot-press fabrication and machining processes, and the sintering is a key process, which governs the properties of the ceramic tool materials as well as the components and content. However, sintering is a very complicated processes, most sintering theory model is based on the simple assumption of particle shape and the mass-transport mechanisms. With the rapid development of the computer simulation technology and the computational material science, modeling and numerical simulation of ceramic sintering process become a novel way to investigate the sintering processes on the micro-scale or macro-scale. Monte Carlo Potts' model is vastly applied to simulate the solid-phase sintering processes of ceramics. Because of no assumption of the particle shape, the model can be properly used to simulate the mass-transport mechanisms. In this paper, the new Monte Carlo Potts' model is proposed to investigate the two-phase systems, which is based on the Potts' model of the description of the single-phase sintering. The new simulation algorithm has been utilized to simulate the microstructural evolution in the two-phase ceramic tool material sintering processes without considering the presence of pores. Three types of interface and three types of grain boundary energy are considered in the new simulation algorithm. At the same time, the cell with the 25 discrete sits is described successfully, which describe the initial grain size of preparation of ceramic tool materials. The sintering mechanism is also discussed.