The invention provides a technological process of an FPP mill finish grinding system, which solves the technical problem in the known grinding technology. The technical points are that a material procedure classification is carried out on materials ground by the FPP mill via a dumping double-deck vibrating sieve; coarse-grain materials on a first layer of sieve return to a raw material belt conveyor as the raw material for the FPP mill to grind; the fine grains on the second layer of sieve and the fine-grain materials separated by a powder concentrator are used as backfill materials of the FPP mill; when the backfill materials are excessive, a part of fine-grain materials is extracted and returned to the raw material belt conveyor as the raw materials; 50% or more of finished products in the final mixed powder below the second layer of sieve are separated by the powder concentrator and then stored in the finished product warehouse; and the fine grains as the backfill materials are sent to the FPP mill and ground. The technological process of grinding-sieving, and powder selecting-grinding is performed in cycles. Finally, a non-balling grinding method is realized.