Facing increasingly strict environmental regulations on transportation fuels, China National Petroleum Corporation (CNPC), the second largest supplier of petroleum products in China, needs to upgrade its transportation fuels. Using the scenario-based analysis method, this paper analyzes how the output and emission related properties, including cetane number, and sulfur and aromatics contents of diesel produced by CNPC, will vary with changes in the confi guration of diesel production units in the next 5-10 years. The results showed that, to upgrade its diesel, CNPC needs to adjust its diesel pool by decreasing the share of fl uid catalytic cracking (FCC) diesel and increasing the shares of hydrocracking (HDC) and hydrotreating (HDT) diesel. Furthermore, to produce ultra-low-sulfur diesel, straight-run diesel as well as poor diesel blendstocks such as FCC diesel and coker diesel should be hydrotreated before being blended into finished diesel. Developing highly efficient HDC and HDT catalysts and corresponding processes is the key to CNPC economically producing more and cleaner diesel.