A new kind of distributed fiber optic sensor is introduced in this paper.On the base of mode coupling between two orthogonal fundamental modes of HiBi polarization maintaining fiber,and using the FMCW technique,a simple equation to determine the locations of pressure points on the fiber is derived.This new kind of method is so unique that the locations of pressure points on the fiber have relations only with the length of the fiber and the frequency of the beat frequency wave.At the same time,using of some techniques,the experimental system has high spatial resolution and locating precision.The research shows that this kind of method has latent application value in many fields.