The invention discloses an aluminum alloy formwork trapezoid cross section profile and a unit formwork structure of an aluminum alloy formwork. The aluminum alloy formwork trapezoid cross section profile is an integrally-formed aluminum alloy abnormal-shaped plate and is composed of a groove body and a group of longitudinal reinforcing ribs, wherein the groove is formed by a rectangular panel and two opposite longitudinal side frames on the back face of the panel, and the longitudinal reinforcing ribs are evenly distributed at the bottom of the groove body. The unit formwork structure of the aluminum alloy formwork comprises the aluminum alloy formwork trapezoid cross section profile, transverse side frames, transverse reinforcing ribs and corner reinforcing blocks. The aluminum alloy formwork trapezoid cross section profile and the unit formwork structure of the aluminum alloy formwork, the structure is clear, forming is easy, later-period machining amount of the formwork is small, the machining cost is reduced, it can be ensured that the formwork is low in weight, safe to use and long in service life, the construction efficiency is improved, standardized, systematic and industrial production is easier, formwork assembly and disassembly are fast, easy and convenient, installation is firm and reliable, the construction efficiency is high, and the construction cost is low.