1.The dredger could be divided into bucket type and pump suction type. Bucket type dredger is applied for waterways with high percentage of clay and gravels, while pump suction type can only be used for terrains with low percentage of clay and gravel. 2.Iron ore need to be retrieved firstly by magnetic separator if the percentage is high in the raw ore, then gold, diamond,zirconium will be concentrated. 3.The key part for the diamond dredger is pulsating jigger. The deal capacity decide the quantity of jigger. We learn the jigger’s technology from one engineer of South Africa. Now the diamond dredger is widely used in Africa.