The invention discloses an optimal control method for a grinding process in a cement plant. By collecting grinding process signals and taking the advanced control as the core, the method realizes automatic control of material level and material level distribution, automatic control of circulating load and ventilation and also realizes optimization of material level of every bin in the mill, optimization of material velocity, optimization of circulating load and ventilation and also realizes output control of feed quantity, rotational speed of a powder-choosing machine and the rotational speed of a fan. The method optimizes the whole grinding process and realizes maximum time-production operation of the grinding process and minimum grinding unit consumption. At the same time, the failure of the grinding process is diagnosed, the safety of the grinding process is estimated, the grinding process is evaluated and analyzed, and the reasonable suggestion is given to the operation of the grinding process, thus assuring a continual, stable, safe and economical operation of the grinding process. The method can be widely used in the grinding process in the cement plant or in similar grinding processes in other fields.