Abstract: Flocculation adding selection-functional magnetic seeds(particles)is a new technology developed in recent years used for dressing of fine weak magnetic iron ore.The principle of the technology lies upon the interaction among fine particles distributed in complicated suspension system.The technology is actually a good combination of flocculation process with separation process adding selection-functional magnetic seeds,to strengthen aggregates formation.The paper describes the desliming test on Tilden iron ore and gives out the final desliming indexes and the research conclusion of test.