The invention relates to the field of building formworks, in particular to a quick assembling-disassembling plastic building angle adjustable formwork which is characterized in that the angle adjustable formwork comprises two face plates which are hinged together, the other ends, parallel to a hinged shaft, of the two face plates are provided with outer side longitudinal rib plates which are perpendicular to the face plates and parallel to the hinged shaft, the two ends of each outer side longitudinal rib plate are provided with outer side horizontal triangle rib plates which are perpendicular to the face plates and the hinged shaft, and the outer side longitudinal rib plates and the outer side horizontal triangle rib plates are respectively provided with at least one or more inserting pin holes which are connected with an adjacent formwork. The formwork can be freely adjusted in the range of 60-300 degrees and be adaptive to different concrete wall corners, wood materials are of no need, resources are saved, recycling and reusing can be achieved, environment is protected, iron screws are of no need, on-site manufacturing is of no need, and assembling and disassembling are convenient and quick.