The invention relates to a smelting reduction recovery and thermal refining method for a rare-earth-niobium-containing slag mixture and belongs to the field of non-blast furnace ironmaking and resource comprehensive utilization. The smelting reduction recovery and thermal refining method for the rare-earth-niobium-containing slag mixture comprises the following steps of (1) mixing rare-earth-containing blast furnace slag and niobium-containing molten steel slag to form the rare-earth-niobium-containing slag mixture and controlling the temperature of the rare-earth-niobium-containing slag mixture within a set temperature range; (2) injecting oxidative gas and conducting smelting reduction to reduce iron oxide into metallic iron fully; and (3) conducting separation and recovery according to different reaction devices. According to the method, the rare earth, the calcium component, the niobium component and the phosphorus component in the slag mixture can be efficiently recycled; cold-state niobium-rare-earth-iron-containing materials can be processed and at the same time thermal refining of the slag can be realized, so that the efficient resource comprehensive utilization can be achieved. The method is short in reaction time, high in metal recovery rate, low in production cost, strong in raw material adaptability, large in processing capacity, friendly with environment, high in economic income and capable of solving the problems of efficient recovery and utilization of metallurgical resources and heat energy effectively.