A double-sided machining laser machine tool is provided for machining a workpiece having opposite first and second machining surfaces. The machine tool includes a laser machining apparatus and a mechanical arm. The laser machining apparatus includes a laser source, a light guiding-and-focusing lens assembly, a three-axis moving stage, an optical inspection device, and a control device. The control device drives the three-axis moving stage moving the workpiece to a machining horizontal coordinate and a machining altitude according to a current horizontal coordinate and a current altitude of the work piece. The control device drives the laser source and the light guiding-and-focusing lens assembly focusing the laser light to the first machining surface. The mechanical arm is controlled by the control device. When the machining of the first machining surface is finished, the mechanical arm flips over the workpiece to allow the laser machining apparatus to machine the second machining surface.