We in this study prepared carbon supported Pd (Pd/C) nanocatalyst using pretreated carbon by different concentrations of hydrochloric acid, nitric acid, tartaric acid and hydrogen peroxide, respectively. The nanocatalyst was used for hydrogenation of nitrobenzene. The catalytic activity and microstructure of Pd/C catalyst were characterized by High Performance Liquid Chromatography (HPLC), scanning electron microscope (SEM), High power transmission electron microscopy (HTEM) and X-ray Diffraction (XRD). Results showed that the order of catalytic activity was as follows: Pd/C (C₄H6O6) < Pd/C (HCI) < Pd/C (HNO₃) < Pd/C (H₂O₂). The values for specific surface area, pore size and pore volume all decreased after pretreatment by HCl and HNO₃, and presented a slight increase after pretreatment with H₂O₂. The dispersion performance of particles in Pd/C catalysts obtained with 25% hydrogen peroxide pretreatment was better and these particles' mean size was 8.0 nm. Pd crystallization degree for catalysts was lower after hydrogen peroxide pretreatment, and the crystalline grains were smaller.