The effect of preoxidative treatments on the reducing characteristics of ShenHua (SH) coal char and the evolution of surface nitrogen-containing complexes during the reducing process under different temperature conditions were investigated using temperature-programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS). The SH samples were oxidized to different conversion degrees (0.15, 0.22, 0.32, 0.42, 0.52, 0.73, and 0.89) under an O-2 atmosphere, and the reductivity of each char sample was considerably enhanced after the preoxidative treatment. This phenomenon could be attributed to the generation of active sites and oxygen-containing complexes on the SH particle surface during the oxidation process. The preoxidized samples were obviously more reactive than the raw char, and per unit mass almost all the preoxidized samples could consume more NO than SH raw char under the same experimental conditions. The entire TPR process could be divided into the following four sections: (a) the reversible physical adsorption stage, (b) the heterogeneous reaction stage, (c) the multireaction stage, and (d) the equilibrium reaction stage. The primary reaction path at each stage could be summarized using the TPR and XPS results. The evolution of the C(N) and the variation in the elemental distribution (C, O, and N) during the TPR process were investigated by XPS. The results showed that N-Q was the most stable organic structure of the nitrogen-containing complexes on the particle, and the decomposition of N-6, N-5, and N-Q occurred when the reaction temperature reached 1173 K. The total amounts of N-Q, N-6, and N-5 decreased when the reaction temperature exceeded 1173 K, indicating interaction between the nitrogen-containing complexes occurred. Meanwhile, prior to the attachment of NO molecules to the char particle surface and forming C(N), more NO molecules were consumed by CO at this temperature. The results in this research clarified the effect of the conversion degree on the char reductivity and the primary reduction reaction path under different temperature conditions, providing a technical framework for the reducing process of air-staged combustion technology.