The invention discloses a trunk side-wing motion plate (7) of a retractable top automobile, which includes a side-wing body (1), a rubber torsion plate (2), a concave idler wheel (3), a shaft (4) and a frame (5); the side-wing plate body (1) is connected with a trunk main cover plate (6) by the rubber torsion plate (2); the concave idler wheel (3), the shaft (4) and the frame (5) are arranged on the bottom surface of the side-wing plate body (1); the concave idler wheel (3) arranged on the frame (5) rolls on the corresponding track in the vehicle body at the shaft (4). The side-wing motion plate (7) motions together with the trunk main cover plate (6), ensuring the retractable top not to be exposed by folding to the rear motion mechanism part of the truck thus the jointing between the trunk and the rear part of the seat looks more beautiful. The invention has the function of decoration and airtightness on the aspect of the esthetics.