True three-dimensional dynamic state display is a main goal of display. 3D real image of object can be observed through double concave sides system. Based on the phenomenon, a new scheme about 3D display is put forward: filming is base on one concave side and 3D display is based on double concave sides system. The scheme can achieve true three-dimensional dynamic state display. Its path of image formation rays simulates the path of rays in real image of object observed through double concave sides system. The scheme has feasibility. The concave sides in the scheme need to satisfy concrete condition: when the distance between the two apexes of concave sides is equal to 3/2 or 1/2 times of radius of curvature of the concave sides, 3D image can be seen at the sketched hole. The ranges of angle are104.48°and 138.59°.