The invention designs the center low-grade bauxite dressing method, takes the center low-grade one water duralumin stone bauxite as the raw material, the main point is uses the 'selective rubbing, the graduation, escapes the putty, the concentration, the narrow rank flotation process' technical process, the selective rubbing uses the ball mill or the vibration rub; The graduation is separates the qualified large grain ore concentrate, chooses water used grain-by-grain selection flowing; escapes the putty, the concentration is carries on the escapes the putty to the ore slime which is smaller than 10mu m and to cause the pulp concentration, satisfies the pulp density request of the following flotation process, uses the water power cyclone; The narrow rank flotation process uses the flotation process craft, the flotation reagent is the ore-dressing;the catche receive medicinal preparation is the fatty acid, the dispersing agent is the sodium carbonate,merges the graduation work obtained large grain ore concentrate with the flotation concentrate and final obtain the ore concentrate,the aluminum silicon ratio in the large grain ore concentrate is bigger than 9, the production rate 30~50%, the Al2O3returns-ratio 40~50%, the mix ore concentrate aluminum silicon ratio is 9~10, the Al2O3returns-ratio is bigger than 88%.The technical process structure is simple,the production cost is low, the movement is steady, the target is stable, has a stronger adaptiveness to the center low-grade one water duralumin stone bauxite.