A scanning system for three-dimensional imaging, comprising: a bench for supporting thereon a subject to be scanned, wherein the bench is adapted to be driven to perform at least a first movement along the Y axis of a XYZ orthogonal coordinate system, wherein in the XYZ coordinate system every two of the X axis, the Y axis and the Z axis are perpendicular to each other; an L-shaped gantry frame (21, 212), movably mounted at a lateral side of the bench, wherein the gantry frame (21, 212) is adapted to be driven to perform at least a second movement in said Y-axial direction of the XYZ orthogonal coordinate system; said gantry frame including a first gantry frame and second gantry frame connecting perpendicular to the first gantry frame so as to form the L-shaped gantry frame, said second gantry frame crossing the bench in the X-axial direction; a light source, movably mounted on the gantry frame, for emitting one of the group comprising a radiation beam and a radiation beam array, wherein the light source is adapted to be driven to perform a movement on the second gantry frame (21,212) along the X axis, wherein the light source is further connected to a rotatable unit, the rotatable unit driving the light source within a limited angular range to perform a first rotation about an X axis and a second rotation about a Y axis, in which the X axis is perpendicular to the Y axis; a sensor for receiving the beam emitted by the light source, movably mounted at a side of the bench opposed to the subject to be scanned with respect to the bench, wherein the sensor is adapted to be driven to perform at least a third movement in said Y-axial direction of the XYZ orthogonal coordinate system; and a control unit, electrically coupled with the gantry frame (21, 212), the light source and the sensor, for controlling movements of the gantry frame (21, 212), the light source, and the sensor, wherein the control unit is adapted such that the first movement of the bench, the third movement of the sensor and the second movement of the gantry frame (21, 212) can be performed independently, wherein the control unit is electrically coupled with a first rotation-driving unit for driving the gantry frame (21, 212) to perform a third rotation about the X axis, and wherein the control unit is further electrically coupled with at least another first rotation-driving unit for driving the gantry frame (21, 212) to perform a fourth rotation about the Y axis and a fifth rotation about the Z axis, in which the X axis, the Y axis and the Z axis are mutually perpendicular to each other; and wherein the control unit is adapted to reconstruct a tomosynthesis image. a bench for supporting thereon a subject to be scanned, wherein the bench is adapted to be driven to perform at least a first movement along the Y axis of a XYZ orthogonal coordinate system, wherein in the XYZ coordinate system every two of the X axis, the Y axis and the Z axis are perpendicular to each other; an L-shaped gantry frame (21, 212), movably mounted at a lateral side of the bench, wherein the gantry frame (21, 212) is adapted to be driven to perform at least a second movement in said Y-axial direction of the XYZ orthogonal coordinate system; said gantry frame including a first gantry frame and second gantry frame connecting perpendicular to the first gantry frame so as to form the L-shaped gantry frame, said second gantry frame crossing the bench in the X-axial direction; a light source, movably mounted on the gantry frame, for emitting one of the group comprising a radiation beam and a radiation beam array, wherein the light source is adapted to be driven to perform a movement on the second gantry frame (21,212) along the X axis, wherein the light source is further connected to a rotatable unit, the rotatable unit driving the light source within a limited angular range to perform a first rotation about an X axis and a second rotation about a Y axis, in which the X axis is perpendicular to the Y axis; a sensor for receiving the beam emitted by the light source, movably mounted at a side of the bench opposed to the subject to be scanned with respect to the bench, wherein the sensor is adapted to be driven to perform at least a third movement in said Y-axial direction of the XYZ orthogonal coordinate system; and a control unit, electrically coupled with the gantry frame (21, 212), the light source and the sensor, for controlling movements of the gantry frame (21, 212), the light source, and the sensor, wherein the control unit is adapted such that the first movement of the bench, the third movement of the sensor and the second movement of the gantry frame (21, 212) can be performed independently, wherein the control unit is electrically coupled with a first rotation-driving unit for driving the gantry frame (21, 212) to perform a third rotation about the X axis, and wherein the control unit is further electrically coupled with at least another first rotation-driving unit for driving the gantry frame (21, 212) to perform a fourth rotation about the Y axis and a fifth rotation about the Z axis, in which the X axis, the Y axis and the Z axis are mutually perpendicular to each other; and wherein the control unit is adapted to reconstruct a tomosynthesis image.