The present invention relates to a Hall Principle-based LED lit mechanical keyboard switch comprising a keymodule, permanent magnet, housing, LED lamp, Hall switch, elastic strip, top cover and spring; the keymodule consists of a plunger and a slider, the plunger has a key on top and a first locating pole at bottom; the slider has magnet mounting slot on its side wall; a second locating pole is provided at the bottom center inside the housing, the second locating pole is provided with a guide hole at its center, and a LED lamp mounting hole is provided on one side in the housing; Hall switch mounting hole and plunger slideway are provided on the neighboring side next to the side of the housing on which LED lamp mounting hole is provided.