This paper describes idioms of the northern Zhuang language. Zhuang idioms are analyzed into two major types, based on syntactic structure: trisyllabic idioms and polysyllabic idioms. Tri-syllabic idioms are short, fixed common expressions consisting of a single predicate. The polysyllabic idioms comprise tetrasyllabic idioms, pentasyllabic idioms, hexasyllabic idioms, and heptasyllabic idioms. The polysyllabic idioms display four syntactic patterns, i.e., serial pattern, causative pattern, topicalized pattern, and condensed pattern. Semantically, the meanings of Zhuang idioms are not the sum of their component part but must be metaphorically interpreted as a whole. The function of Zhuang idioms is to increase effectiveness and rhetorical force in oral and literary communication.