In view of the production problems of the original vertical sand silo classification tailings filling system of a gold mine, such as low filling concentration, large amount of slurry flow, low strength of backfill body and insufficient storage capacity of the tailings reservoir, the optimization scheme of vertical sand silo filling system was studied. The -200 mesh ultrafine tailings were used for filling, the efficient flocculation settlement structure of ultrafine tailings and the homogenization mixing system of ultrafine tailings were studied, and the application effect was tested in the field. The results show that: 1) The spiral feed flocculation settlement center cylinder developed for ultrafine tailings can effectively realize the efficient flocculation settlement of ultrafine tailings, the overflow water at the top of the sand silo is clarified, the solid content is less than 200 ppm, and the mineral processing can be carried out directly in the recycling plant; 2) When the concentration of sand at the bottom of the sand silo reaches 60%, the slurry as a whole presents paste characteristics with good fluidity, no segregation occurs, and the bleeding rate decreases significantly; 3) The super-fine tailings slurry and cement are fully mixed in the mixing system, which realizes the efficient utilization of cement, good homogenization effect of filling slurry and high filling quality. By realizing the high quality filling of ultrafine tailings, a solid foundation is laid for the construction process of tailless mine.