The invention discloses a smoke gas circulation system of an oxygen-enriched combustion boiler. The smoke gas circulation system of the oxygen-enriched combustion boiler comprises a primary smoke gas circulation system, wherein the primary smoke gas circulation system comprises a boiler (10), a preheater (20), a smoke gas processing device (30) and a primary air circulation pipeline (40); a primary air fan (50) and a coal grinding machine (60) are sequentially arranged in the primary air circulation pipeline; the smoke gas circulation system of the oxygen-enriched combustion boiler also comprises primary air circulation branch pipes (41); the primary air circulation branch pipes are connected in parallel onto a part of the primary air circulation pipeline between the primary air fan and the coal grinding machine; the primary air circulation branch pipes also pass through the preheater; the primary smoke gas circulation system also comprises a primary air oxygen injector (70) arranged in a primary air circulation pipeline between the primary air fan and the coal grinding machine. The smoke gas circulation system of the oxygen-enriched combustion boiler determines the position of the oxygen injector; the optimization of the efficiency, the safety and the economy of the oxygen enriching combustion boiler is realized.