Abstract: Secret societies proliferated vigorously in the social and historical environment of the Qing dynasty. An increasingly expansive “floating population” was the social foundation that allowed secret societies to survive and spread. The vagrants’ culture was rooted in and shaped by folk culture, which they collectively embodied. The concept of the code of brotherhood, known as “jianghu yiqi”(code of brotherhood on the rivers and lakes) played up in the folk literature and drama spread widely in the underworld. Secret society members absorbed this code and formed their own characteristic concept of morals and law. The secret societies belonged to the underworld and could not assimilate nutriment from elite culture, and folk culture was the natural elements that they used to form their own culture. This article narrates the secret societies’ code of brotherhood from the following aspects: rites, enigmatic language, secret signals, and prevailing figures. The secret societies’utilization and reconstruction of folkloric concepts of brotherhood served the goals of their organizations, activities, and rebellions.