The utility model discloses a split type double -light -path key switch and mechanical keyboard, the key switch includes the key switch body, sets up LED radiated element and light receiving element on the PCB board, and the key switch body includes the casing and sets up the handle of pressing on the casing, separates through the first device that is in the light between LED radiated element and the light receiving element, the top of LED radiated element is equipped with first light conductor, and light receiving element's top is equipped with the second light conductor, is equipped with printing opacity portion and first reflection of light portion on the first light conductor, is equipped with second reflection of light portion on the second light conductor, according to being equipped with the second device that is in the light on the handle. The utility model discloses a LED radiated element not only can be realized the function of being shaded can realizing the switch conduction together with light receiving element moreover, makes whole casing can reserve enough big space, moreover through the transmission of two light conductors, has improved the stability of optical transmission, has reduced the cost and the technological requirement of key switch, has improved mechanical keyboard's precision and life simultaneously greatly.