Abstract: In order to realize the quality upgrading of national Ⅵ gasoline, the problems existing in the production of national ⅥA standard gasoline were analyzed. The main reason was that the high olefin content of catalytic gasoline affected the blending of national ⅥA standard gasoline. Through the optimization of operation conditions in heavy oil catalytic cracking unit, the application of new olefin reducing catalyst, the optimization of operation conditions in gasoline hydrogenation unit and optimum processing of residual C₅ in gasoline etherification unit, the olefin content in gasoline of two heavy oil catalytic cracking units decreased from more than 35% to about 30%, the olefin content in gasoline of gasoline hydrogenation unit decreased from 24.7% to 18.9%, and the olefin content in gasoline of gasoline semi-finished tank decreased from 25.7% to 21.5%, which met the blending needs of national standard ⅥA gasoline and realized the quality upgrading of national Ⅵ gasoline.