The invention provides a photoelectric thin shaft mechanical keyboard switch, and relates to the photoelectric keyboard switch technology field. The technical problem of the photoelectric keyboard of poor paragraph feeling during pressing of a button is solved. The photoelectric thin shaft mechanical keyboard switch comprises a cover plate, a base, a button, a reset spring, and a photoelectric coupler. The photoelectric thin shaft mechanical keyboard switch also comprises a torsional spring, which comprises a fixing arm, a barrier arm, and a spiral segment. The fixing arm is fixedly disposed on the base, and the end part of the barrier arm is disposed in the sliding path of the button, and the paragraph feeling is realized by the button sliding upwards and downwards to be contacted with the barrier arm. When a human finger presses the button downwards, the button moves downwards, and during the above mentioned process, the torsional spring is used to provide upward resistance for the button, and then when the pressure applied by the finger on the button disappears, under common springback action of the reset spring and the torsional spring, the button moves upwards quickly, and is reset, and therefore when the button moves upwards and downwards, the touch feeling of the finger is strong, and the paragraph feeling is obvious.