Abstract: Optical fiber sensors are sensitive to refractive index, small in size and easy to be integrated. Because the resonance peak and amplitude of the transmission spectrum are very sensitive to the external environment, they have attracted much attention in the sensing field. In this experiment, a long period fiber grating (LPFG) was prepared in a single-mode fiber. According to the experiment, with the increase of the refractive index of the solution, the corresponding wavelength appears blue shift and the refractive index sensitivity is −84.4 nm/RIU. With the increase of the ambient temperature, the corresponding wavelength appears red shift and the temperature sensitivity is 78.17 pm/℃. With the increase of the applied stress, the corresponding wavelength appears blue shift and the stress sensitivity is −5.72 pm/με. As a new optical device, LPFG plays an important role in the miniaturization of structures and the diversity of functions.