A detachable and collapsible double-gantry mechanical arm surgical robot, comprising an operating table having a longitudinal dimension, a transversal dimension and a vertical dimension, wherein X-direction guidance control devices are arranged in pairs on both longitudinal sides of the operating table; main swing arms are connected to the operating table through a main connecting base; a main push rod is installed on the main connecting base; the main push rod is connected to a lower end of the main swing arm; the main connecting base and an upper end of the main swing arm are connected to a main positioning lock; the main swing arm is further connected to a Y-direction guidance device; and the Y-direction guidance device is connected to a Z-direction guidance control device, wherein a main gantry mechanical arm is formed, main positioning lock locks and supports the main gantry mechanical arm; secondary swing arms are connected to the operating table through a secondary connecting base installed on the X-direction guidance control devices, and a cross beam is connected between the secondary swing arms through a quick-change mechanism, wherein a secondary gantry mechanical arm is formed; and a secondary push rod is connected between the secondary connecting base and the secondary swing arm; the secondary push rod is connected to a lower end of the secondary swing arm; and a secondary positioning lock for increasing rigidity of the secondary swing arm is arranged between the secondary swing arm and the secondary connecting base such that the secondary positioning lock locks and supports the secondary gantry mechanical arm; wherein the longitudinal dimension of the operating table is defined as X-direction; the transversal dimension of the operating table is defined as Y-direction and, the vertical dimension of the operating table is defined as Z-direction; X, Y, Z reference frame formed by the X-direction, Y-direction, Z-direction is orthogonal; and characterized in that the main connecting base is installed on the X-direction guidance control devices; the main push rod pushes the main swing arm to rotate around a main swing axis parallel to the Y-direction; the secondary push rod pushes the secondary swing arm to rotate around a secondary swing axis parallel to the Y-direction. secondary swing arms are connected to the operating table through a secondary connecting base installed on the X-direction guidance control devices, and a cross beam is connected between the secondary swing arms through a quick-change mechanism, wherein a secondary gantry mechanical arm is formed; and a secondary push rod is connected between the secondary connecting base and the secondary swing arm; the secondary push rod is connected to a lower end of the secondary swing arm; and a secondary positioning lock for increasing rigidity of the secondary swing arm is arranged between the secondary swing arm and the secondary connecting base such that the secondary positioning lock locks and supports the secondary gantry mechanical arm; wherein the longitudinal dimension of the operating table is defined as X-direction; the transversal dimension of the operating table is defined as Y-direction and, the vertical dimension of the operating table is defined as Z-direction; X, Y, Z reference frame formed by the X-direction, Y-direction, Z-direction is orthogonal; and characterized in that the main connecting base is installed on the X-direction guidance control devices; the main push rod pushes the main swing arm to rotate around a main swing axis parallel to the Y-direction; the secondary push rod pushes the secondary swing arm to rotate around a secondary swing axis parallel to the Y-direction.