Abstract: In view of problem that traditional slope monitoring cannot master process of development, deformation and failure of slope in real-time and dynamically according to actual slope engineering, the paper proposed a method to set fiber grating displacement sensor on potential sliding surface in open pit mine engineering to collect displacement data accurately and make early warning. The method masters deformation failure process of the slope based upon the detected data, and then discriminates sliding time of landslide according to development and change law of the slope so as to make early warning in time and accurately. The test result shows that the fiber grating displacement sensor applied in slope monitoring can obtain dynamic displacement monitoring curve and make early warning accurately and effectively.