The invention discloses a system for fluidized oxidizing/reducing roasting modification of titaniferous iron concentrate and a roasting process. A fluidized bed oxidation reactor is adopted for the oxidizing roasting of titaniferous iron concentrate powder, and fluidized air is preheated by a hot blast heater and mineral powder is preheated by a multistage cyclone preheater so as to provide heat for oxidizing roasting; the oxidized mineral powder enters the fluidized bed reduction reactor for reducing roasting, and heat is provided for the reducing roasting through heating coal gas by a coal gas preheater; and latent heat of unreacted reducing gas in roasting tail gas of the reduction reactor is firstly released through combustion in a combustion chamber, one path of hot flue gas after the combustion is mixed with the tail gas of the oxidation reactor and then enters the multistage cyclone preheater to exchange heat with the cold titaniferous iron concentrate powder, heat is recycled while the titaniferous iron concentrate is preheated, and the other path of hot flue gas is used for preheating cold coal gas to warm the fluidized coal gas entering a reducing furnace so as to strengthen a reducing condition. The system has the advantages of high oxidizing/reducing efficiency, high heat utilization efficiency in a roasting process and the like.