Abstract: The objective of the present study was to investigate the removal characteristics of NOx from the practical diesel engine exhaust over NOx storage and reduction (NSR) catalysts. A series of xCe(25-x)Ba/γ-Al2O3(x=8%-12%, 25-x=17%-13%) and Pt10Ce15Ba/γ-Al2O3 NSR catalysts were prepared by an incipient wetness method. The effect of metallic Ce and Ba on their microstructure and catalytic properties was investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and Transmission Electron Microscope (TEM) analysis. It was found from the catalyst characteristic with the xCe(25-x)Ba/γ-Al2O3 catalysts that the size of BaO became smaller and dispersed better when the value of x increasing from 8 to 10, while the size of BaO were larger and the dispersion were getting worse when the value of x increasing from 10 to 12. The size of BaO was smallest and the dispersivity of BaO was good when the value of x was 10. TEM characterizations of 10Ce15Ba/γ-Al2O3 catalyst indicated that the diameter range of CeO2 and BaO was from 5 nm to 20 nm. According to the results of analysis, the 10Ce15Ba/γ-Al2O3 and Pt10Ce15Ba/γ-Al2O3 catalysts were chosen to be coated on cordierite honeycomb ceramic device by an incipient wetness method. Then the catalytic activity of the 10Ce15Ba/γ-Al2O3 and Pt10Ce15Ba/γ-Al2O3 catalysts for removal of NOx was characterized based on bench tests. In order to facilitate the systematic study of the performance of 10Ce15Ba/γ-Al2O3 and Pt10Ce15Ba/γ-Al2O3 catalysts on NOx removal from diesel engine exhaust, and reduce its impact on the performance of diesel engine and the structure reformation of exhaust system, the experimental research on NOx removal with NSR technology by the bypass way was carried out. The diesel engine was operated at the revolution of 2400 r/min and the engine load was 10%, 25%, 50%, 75% and 100%. The results showed that NOx was stored as nitrites or nitrates on the storage components of 10Ce15Ba/γ-Al2O3 catalyst with engine load less than 50%, and the maximum conversion rate of NOx over 10Ce15Ba/γ-Al2O3 catalyst was up to 80%. With the engine load more than 50%, previously adsorbed nitrate species started to decompose and the NOx species were reduced to N2 by CO, HC or other reducing agent from practical diesel engine exhaust on the surface of 10Ce15Ba/γ-Al2O3 catalyst, and the maximum conversion rate of NOx over 10Ce15Ba/γ-Al2O3 catalyst was up to 60%. The possible reason was that the performance of NOx reduction was improved due to Ceria. In comparison with 10Ce15Ba/γ-Al2O3 catalyst, Pt10Ce15Ba/γ-Al2O3 catalyst showed better activity for NOx storage and reduction. With the engine load less than 50%, the maximum conversion rate of NOx over Pt10Ce15Ba/γ-Al2O3 catalyst was close to 100%, and the maximum conversion rate of NOx over Pt10Ce15Ba/γ-Al2O3 catalyst was up to 75% with engine load more than 50%, which can be included that the NOx storage and reduction performance was greatly improved by adding Pt. The experimental results can provide a reference for optimum design and application of NSR catalyst in the field of diesel exhaust after-treatment system.