Predesilicification-bauxite dressing-Bayer process is a new technical process in alumina industry proposed firstly in the world. The study on the disaggregation between alumina mineral and silica mineral in the predesilicification presents the theoretical basis for the new process. The study on the different reaction features of hydrated sodium aluminosilicate produced in different temperature with additive lime in atmospheric pressure provides the theoretical basis for its technical and economical feasibility. Some key techniques such as avoidance of bauxite over grinding and gradation of the small particles in bauxite dressing are investigated. The method of the new process in use is mentioned.