In cement industry, many grinding up systems are on operating now. The tradition process of tube mill grinding system is high energy consumption, so it’s low efficiency, especially in the final cement grinding process. The value and advantage of slag is recognized more and more, but it’s difficult to be grinded up. Furthermore, the disadvantage and shortages to grind up clinker compounded with slag to produce cement are obvious and adopted. The best process is to grind up slag, clinker separately. Then, these two kinds of powder are compounded by a mixer. Hereby, it introduces a design of the process to grind up clinker, slag by one roller mill.