The invention relates to the technical field of copper smelting, and discloses a compound reducing agent for fire refining of copper. The compound reducing agent is characterized in that every 100 parts by mass of compound reducing agent is prepared from 8-12 parts of coal, 45-55 parts of petroleum coke and 35-45 parts of composite biomass carbon. According to the compound reducing agent, on the premise of environment friendless and low cost, the content of sulphur and the content of ash are reduced, high activity is achieved, and the reducing efficiency is high.