Abstract: An automatic robotic arm system and a coordinating method for robotic arm and computer vision thereof are disclosed. A beam-splitting mirror splits an incident light into a visible light and a ranging light and respectively guides to an image capturing device and an optical ranging device arranged in the different reference axes. In a calibration mode, a transformation relation is computed based on a plurality of the calibration postures and corresponding calibration images. In an operation mode, a mechanical space coordinate is determined based on an operation image and the transformation relation, and the robotic arm is controlled to move based on the mechanical space coordinate.