Abstract: Production of clean diesel fuel with a low even ultra-low sulfur content and high cetane number is becoming an urgent task for refineries over the world. Among the various methods for producing clean diesel fuel，improving catalytic activity of hydrotreating catalysts is the most effective and economical one. Starting from the active phase theory for transition metal sulfide hydrotreating catalysts and the pathways of hydrodesulfurization and hydrodearomatization reactions，this review summarizes various approaches to improving the activity of hydrotreating catalysts to meet the needs of diesel fuel deep hydrodesulfurization and hydrodearomatization. The methods reviewed include：(Ⅰ) enhancing hydrogenation performance of active species; (Ⅱ) introducing acidic centers with moderate acidity; (Ⅲ) weakening metal-support interaction; (Ⅳ) improving the dispersion of active species. We conclude that developing a new support with high surface area and moderate acidity and exploring new catalyst preparation methods to increase the dispersion of active species without strengthening metal-support interaction are two of the main routes to further increase performance of diesel hydrorefining catalysts.