Cemented carbides are widely used materials typically for cutting, milling, turning and rock drilling owing to their good balance of hardness and toughness as well as abrasion resistance and heat resistance. In order to find a quantitative way to control the microstructure evolution and mechanical properties in cemented carbides, new thermodynamic and diffusion databases for multi-component cemented carbide are established. Based on the databases, numerical simulations of microstructure evolution during sintering were performed for gradient cemented carbides and cellular cemented carbides. For the gradient cemented carbides, simulated microstructure is compared with the measured one, and the key microstructural parameters are obtained to predict the hardness distribution in the gradient layer. In the case of the cellular cemented carbides, liquid phase migration process and its effect on the composition profiles and microstructure evolution are simulated by means of phase field method. There is a good agreement between simulation and experiment.