The invention provides an M-Z interface light path structure with an all polarization function. The structure comprises a polarizing beam-splitting device, a first polarization-maintaining and transferring device, a first Faraday rotator mirror, a second polarization-maintaining and transferring device, a second Faraday rotator mirror and a first polarization-maintaining coupler; the first polarization-maintaining and transferring device comprises a first port, a second port and a third port, wherein the first port receives first polarized light outputted by the polarizing beam-splitting device, the second port is connected with the first Faraday rotator mirror, and the third port is connected with a first port of the first polarization-maintaining coupler; the second polarization-maintaining and transferring device comprises a first port, a second port and a third port, wherein the first port receives second polarized light outputted by the polarizing beam-splitting device, the secondport is connected with the second Faraday rotator mirror, and the third port is connected with a second port of the first polarization-maintaining coupler. The structure is suitable for long-distancedistributed fiber sensing, such as being used in the fields of fiber communication trunk monitoring, safety monitoring of a long-distance perimeter, petroleum, natural gas pipelines and the like.