The invention relates to an oredressing method for pertinently reducing content of sesquioxide of iron and aluminum (R2O3) in the collophanite floatation process in advance. The process comprises the following steps of: (1) levigating raw collophanite until grains with the grain size of 0.038mm are more than or equal to 76 weight percent, and controlling the pulp mixing concentration to be 25-40 weight percent; (2) introducing ore pulp into a mineralizing agitation tank of a floatation machine, adding an agent for floating conventional mid-low grade collophanite for pneumatic flotation, ensuring that a spindle speed of the floatation machine is 1,800-2,100r/min, the floating aeration quantity is 0.05-0.10m<3>/h and the floating scraper speed is 20-30r/min, and obtaining phosphate concentrate subjected to rough concentration; and (3) controlling the pH of the phosphate concentrate subjected to rough concentration to be 4.5-5.5, adding a collector for removing R2O3, performing pneumatic flotation for 4 to 8 minutes, removing an impurity of R2O3 from foam, and obtaining base flow, namely a high grade phosphate concentrate product. By the method, the R2O3 content in the concentrate can be obviously reduced, the quality of the phosphate concentrate is improved, and production processes, flows and cost during purification in the subsequent acid making process can be reduced.