Abstract: Bow and arrow was once the main weapon in the battle between the Song Dynasty and the northern grassland nomads.The Wu brothers accumulated rich operational experience in the Song Xia and Song Jin campaigns,and had a deeper understanding and experience of the flexible use of “bow” and “arrow” combat,and improved this tactic in the past.Wu Jie created “Zhuduishi” to use the bow and arrow to “Fanxudieshe”,which means individuals operated the crossbow,the echelon rotation exchanged to shoot,and took the initiative to fight.Wu Lin invented the “Multilayer Array Method” combination by using long guns,bows and arrows to shorten the effective range of the bow and the arrow,which gave full play to the crossbow tactics.He also set up obstacles to block the enemy cavalry and two-wing cavalry guards to complete flexible formation changes.This tactic not only achieved the victory of the Battle of Heshangyuan and the Battle of Xianrenguan,blocked the Jin Dynastys plan to invade Sichuan,effectively ensured the security of the Southern Song Dynasty,but also provided the possibility for the development and utilization of the cold weapons of the later generations.

Key words: the Southern Song Dynasty, Wu Jie, Wu Lin, the crossbow tactics