In this paper, the photonic crystal structure was designed using the doped silicon which has absorption effect on terahertz band. As a result, the light wave in the photonic band gap was absorbed. In addition, the reflective mirror of metal facilitated the combination of the absorption peak of photonic crystal and Fabry-Perot(F-P) resonant absorption peak. Thus, as this structure was not affected by temperature changes in 0.31-0.34 THz band, it could achieve broadband absorption. Moreover, the 0.29-0.31 THz band had the temperature sensing function. By using the commercial electromagnetic simulation software CST2014 to stimulate the optimization parameter, a photonic crystal-based temperature sensor with large incidence angle was designed. The reflectivity would change with the linear variation of temperature.