How to efficiently extract iron from iron-rich nickel slag is the key to the comprehensive reuse of this resource. Coke and bituminous coal are used as reducing agents to carry out a direct reduction of nickel slag to extract iron, to compare the differences of the two reducing agents in the reduction process of nickel slag, to analyze the thermodynamic analysis of the reduction capacity of different reducing media with the help of thermodynamic software, and then to study the effects of the two reducing agents on the change of metallization rate and microstructure evolution of nickel slag reduction process through experiments and characterization. The results show that the high volatile content of bituminous coal will produce the reducing medium mixed with CO-H₂, while the coke is mainly CO reducing medium. The results of thermodynamic analysis show that the reducing ability of CO-H₂ mixture to iron oxide is better than that of pure CO. The results of nickel slag reduction roasting test show that, when bituminous coal is used as reducing agent, the metallization rate of nickel slag pellets could reach 90.20% after 20 min of reduction at 1 300 ℃. When coke is used as the reducing agent, its metallization rate only reaches 72.97%, and the reducing ability of bituminous coal to nickel slag is better than that of coke.