A screw auto-detection and selection device comprises a rotary machine table; a light source generating unit; a recording control unit; a camera detecting unit; and a time scale cam unit. The feature of device is that the camera detecting unit includes a press, an ejecting and a second camera detector. The press has a press arm extending above the notch of the dispatching disk and an elastic press installed at a predetermined position of the press arm. An ejecting has an ejecting pin and a movement limiting unit for ejecting a screw pressed by the press arm so that the screw is aligned to a radiating hole of the light source generating unit.