The present invention discloses a protection method of a distributed optical fiber in a transformer. The protection method comprises the following steps of A attaching an optical fiber and a low-voltage winding conducting wire, and synchronously winding the optical fiber along with the low-voltage winding conducting wire; B measuring the Brillouin frequency shift in the optical fiber, and adjusting the laying position of the optical fiber according to a measurement result; C applying tension at the input end of the optical fiber, and adjusting the laying position of the optical fiber accordingto the Brillouin frequency shift measurement results before and after applying the tension; D applying the tension at the output end of the optical fiber, and adjusting the laying position of the optical fiber according to the Brillouin frequency shift measurement results before and after applying the tension; E then applying the tension at the input end and the output end of the optical fiber simultaneously, and adjusting the laying position of the optical fiber according to the Brillouin frequency shift measurement results before and after applying the tension. The protection method of thepresent invention can solve the insufficiency in the prior art, and can detect and adjust the own stress of the optical fiber accurately.