The invention provides a thermal insulation and decoration large plate for a fabricated building exterior wall. The large plate is provided with an anti-crack mortar internal layer, a thermal insulation layer and an anti-crack mortar external layer in turn from inside to outside; a light steel keel is arranged in the anti-crack mortar external layer, and is a net which is formed by transverse keels and longitudinal keels in an intersection manner; each intersection is in bolted connection or welded connection; a first bolt is fixed to each joint, and is externally connected to a nonmetallic connecting piece; each nonmetallic connecting piece is externally connected to a second bolt, and at least part of each nonmetallic connecting piece is located in the anti-crack mortar external layer. According to the thermal insulation and decoration large plate for the fabricated building exterior wall, provided by the invention, as the light steel keel is added into the large plate, entire strength performance, in particular tensile strength and anti-bending strength, of the large plate are enhanced obviously; as the light steel keel is formed by cold rolling thin steel sheets, the weight added to the large plate is limit, and the requirement for light weight is met.