Hydrogen-based direct reduced iron (HyDRI) produced by fluidized bed has great potential for achieving the target of net-zero carbon in steelmaking. However, when magnetite ores were used as feedstock, several process parameters showed influences on its fluidization and reduction behaviors. To confirm the dominant influencing factors and its optimum process condition, the orthogonal experimental method was conducted in the present study. The result shows that the primary and secondary influencing factors are oxidation temperature, oxidation content, MgO addition amount, and gas velocity. The optimum condition is that the magnetite iron ore is deeply oxidized at 800 °C, mixed with 1.5 wt.% of MgO powder, and reduced in the fluidized bed at a gas velocity of 0.45 m/s.