The invention relates to the field of buildings, in particular to a compound sandwich layer assembled building. The compound sandwich layer assembled building uses building blocks and keels to form an enclosure wall by assembly, further comprises upright posts combined by the keels, a floor cover frame, a roof frame and a ring beam, is specifically assembled by the building blocks (2) of a wall body on the outer side, the U-shaped keel (3), the L-shaped keel (4), screws (5) for series connection, the building blocks (6) of the wall body on the inner side, covering strips (8), thermal insulation material (9), the upright posts (10), a connecting part (11) for the L-shaped keel, fasteners (12), a truss (13), window purlins (41) and door purlins (42), and is characterized in that the vertical surfaces of the building blocks (2) of the wall body on the outer side and the building blocks (6) of the wall body on the inner side are parallel mutually for forming a sandwich layer space (7), and the upright posts (10), the floor cover frame, the roof frame and the ring beam are formed by angle keels (701). The structure is firm and reliable, the energy-saving efficiency is high, the construction is safe and convenient, the industrialized industry scale can be realized, and the performance price ratio is excellent.