This invention relates to a worm gear self-locking clamping device and its usage method. It includes: a housing, a rotating shaft, a worm, a worm wheel, a central shaft, a rotating disk, clamping jaws, and a limiting block; the axes of the worm wheel, the central shaft, and the rotating disk are aligned in a straight line, and the worm, the worm wheel, the central shaft, and the rotating disk are all located inside the housing; the clamping jaws, constrained by the oblique guide groove on the end face of the rotating disk and the radial guide groove on the end face of the housing, achieve synchronous centering clamping. This invention provides a worm gear self-locking clamping device that utilizes the reverse self-locking characteristic of the worm gear to maintain stable clamping even after power is removed, without the need for continuous power supply. This invention has a compact structure, is easy to operate, and has advantages such as reliable self-locking, vibration resistance, and energy saving, making it suitable for harsh working conditions such as high vibration and power outage safety.