One-dimensional photonic crystal exhibits unbelievable performance in designing large-mode-area fiber and fiber Bragg gating for high power fiber laser. However, the property of one-dimensional photonic crystal is sensitive to its structure and refractive index distribution, which may change due to the non-negligible thermal effect resulting from the hyperthermal working condition. In this paper, the thermal effect on one-dimensional photonic crystal is analyzed on the basis of heat transfer theory, Bragg reflection theory and finite element method(FEM). Firstly, with the help of heat transfer theory and finite element method, the temperature fields of the one-dimensional photonic crystal subjected to different heating sources are calculated. By making use of the calculation results, the deformation of the photonic crystal bringing from the temperature field is estimated. Then, the thermal effect on the transmission spectrum of the one-dimensional photonic crystal is analyzed. These studies not only provide important information for the manufacture of high power fiber laser but also may help the designers of fiber laser to find methods of counteracting the thermal effect.