A novel environmentally friendly sulfiding agent SZ 54 was for the first time used for presulfidation of the catalyst in the 2 Mt/a hydrofining unit at Zhenhai Refining and Chemical Company. The application results had shown that the sulfiding agent SZ54 had low smell, high flash point, and safe and environmentally friendly features. The lower decomposition temperature and stepwise chemical decomposition characteristics of this reagent can effectively avoid the reduction of metals and improve sulfur adsorption to meet the needs for sulfidizing the hydrofining catalyst,and is a good reagent worthy of extended application.