The invention relates to a system and a method for desulfurization and denitration integrated treatment and resource utilization for flue gas by red mud, and belongs to the technical field of resourceutilization and environmental protection. The system comprises a desulfurization spray tower, an ozone generator, a denitration spray tower, a slurry mixing tank, a slurry storage tank, a vacuum filter, an ammonia water neutralization tank, an aluminum hydroxide precipitation tank, an ammonia water tank, an aluminum hydroxide storage tank, a filter press, an ammonia distillation tower, a dephlegmator, a cooler, a concentrated ammonia water storage tank, a gypsum precipitation tank and an anaerobic biochemical tank. The flue gas is subjected to desulfurization and denitration treatment by redmud slurry, SO2 and NO in the flue gas are removed, so that SO2 and NO in the flue gas reach the emission standard, aluminum hydroxide in the red mud slurry is recovered by an ammonia precipitant, wastewater is returned to be used for slurry preparation after precipitation and hydration biochemical treatment, and desulfurization and denitration integrated treatment and resource utilization of thered mud and the flue gas are realized.