An embodiment of the invention provides an optical switch matrix and a control method thereof. Through transmitting a first single-mode optical signal and a second single-mode optical signal in an optical communication network through waveguides with the same length in a first mode in the optical switch matrix and processing by the same device, and performing one-time mode conversion, a problem ofrelatively high PDL and DGD of the optical signal in the optical network through processing by the optical switch matrix is settled. Furthermore, through arranging a first crossed waveguide, a secondcrossed waveguide, a third crossed waveguide and a fourth crossed waveguide, a number difference between the crossed waveguides on different waveguides is reduced, thereby further reducing the PDL.