The invention discloses an optical fiber temperature measuring probe of a transformer. The temperature sensor comprises a bottom shell and a top shell which are buckled with each other, a temperature-sensitive optical fiber is installed in the bottom shell, an external thread part is arranged on the outer side of the bottom shell, an internal thread part meshed with the external thread part is arranged on the inner side of the top shell, the surface of the external thread part is wrapped with a capsule layer, and the capsule layer on the top of the external thread part is connected with a first extrusion plate; the top of the internal thread part is movably connected with a second extrusion plate through a clamping pin, the edge of the inner side of the second extrusion plate is connectedwith a sealing ring through an obliquely-arranged elastic piece, and the sealing ring is in sealing contact with the bottom shell. By adopting the optical fiber temperature measuring probe of the transformer, the defects in the prior art can be overcome, and the sealing effect is improved when the probe adopts a split type assembly structure.