This paper studies the emission reduction properties of carbon smoke particles (PM) and nitrogen oxides (NO_X) using cerium zirconium composite oxides. Firstly, the cerium-zirconium composite oxides catalysts were prepared and analyzed by XRD, SEM, ICP and BET. Then the exhaust catalytic treatment experiment was carried out on the self-built Changchai CZ2102 diesel engine test bed. The exhaust temperature of diesel engine was raised to 500ºC by using temperature programmed technology to simulate the exhaust condition of Marine diesel engine to ensure the experimental data is more accurate. Finally, lanthanum was added into the cerium zirconium composite oxide to modify the catalyst to improve its catalytic performance. The exhaust treatment experiment was carried out again, and the experimental data were compared and analyzed Studies show that cerium zirconium composite oxides of NO_X and PM are with high catalytic efficiency which can be further improved after adding lanthanum elements. Therefore, this diesel engine post-treatment technology has a great development prospect.