Chemical looping hydrogen generation based on iron is an innovative method to produce high purity hydrogen and capture CO2 simultaneously. However, carbon deposition of iron ore limits the development. The iron ore modified by K and Cu was employed to suppress the carbon deposition. Experiments were carried out to investigate the effects of the additive amount on carbon deposition and hydrogen purity via carbon release characteristics in a batch fluidized bed. The carbon deposition ratio decreased monotonically with the increasing amount of potassium, but the excess copper loading led to a rise in the ratio of carbon deposition instead. The carbon deposition ratio decreased by up to 84% after adding K and Cu, which is speculated to be closely related to the weight ratio of Fe on the oxygen carrier surfaces. The experimental results at different temperatures demonstrated that 850 degrees C was suitable for the inhibition of carbon deposition and sintering. In addition, the mechanism of inhibition of carbon deposition was proposed in detail and illustrated that it was correlated to the covering of active sites and the reactivity enhancement. Moreover, the carbon deposition ratio of the modified oxygen carrier maintained stable during the cyclic experiments. Therefore, it is feasible to employ the iron ore modified by K and Cu as oxygen carrier to suppress carbon deposition in the chemical looping hydrogen generation.