A method for prolonging the campaign life of a combined blown converter by adopting a metal slag syntactic mushroom head belongs to the technique field of oxygen converter steelmaking. A circular seam type bottom blowing air-supplying element is adopted to replace a capillary permeable brick, thus allowing airflow to concentrate and raising the cooling power on the tip of a nozzle. After well-developed metal mushroom head is formed at the initial campaign stage of smelting process, slag splashing process is carried out immediately to form a slag mushroom head on the surface of the metal mushroom head. After the initial formation of the metal slag syntactic mushroom head, attention is paid on detecting whether the air pressure, P-Q curve of the flow relation, and cold state measurement value have obvious discrepancy; if the discrepancy is larger, the technology is appropriately adjusted to ensure the ventilation property. In the following campaign period, the mushroom head is protected; the mushroom head and hearth height are often detected; the deviation between cold state P-Q curve and the hot sate P-Q curve is detected, thus ensuring that the mushroom head can protect the bottom blowing element effectively in the whole campaign period and having good ventilation property. The method has the advantages of allowing the furnace campaign of the combined blown converter to achieve over 10000 and can reach to 30000 for maximum.