Abstract: The measures for optimal energy saving were suggested and applied for a new 2.5 Mt/a FCC unit of Sichuan Petrochemical Co. Ltd.. The measures for energy saving optimized the coke rate, electricity consumption and steam production both in design and operation. The actual energy consumption after 12 months operation reduced significantly compared with the design values. The unit energy consumption of coking, electricity and 4.0 MPa steam production is reduced by 0.080 8 GJ/t, 0.030 1 GJ/t, and 0.041 GJ/t, respectively. The overall energy consumption of the FCC unit decreases by 0.124 GJ/t. The processing cost for the 2.5 Mt/a FCC unit can save ￥7.5 millions/a. Both the energy saving and the economic efficiency are significant.