The invention relates to the field of optical devices, in particular to a 2*2 mechanical optical switch. The 2*2 mechanical optical switch comprises two sets of four-fiber collimators, and glass prisms capable of being freely inserted and separated are arranged among the four-fiber collimators. In the separating state, light beams of a first optical fiber, a second optical fiber, a fifth optical fiber and a sixth optical fiber are directly coupled to a seventh optical fiber, an eighth optical fiber, a third optical fiber and a fourth optical fiber respectively. In the inserting state, after the light beams are deviated through the glass prisms, the first optical fiber is coupled to the third optical fiber, and at the same time, the second optical fiber is coupled to the fourth optical fiber. Besides, the fifth optical fiber is connected with the sixth optical fiber, and the eighth optical fiber is connected with the seventh optical fiber. A bypass loop is formed by leading the light to the other side from one side only through one displacement optical element. Therefore, the dimensionality of optical fiber alignment adjustment can be reduced, larger positions and angle allowances are allowed, the packing difficulty can be reduced, and the 2*2 mechanical optical switch is especially suitable for being produced on a large scale.