Si and SiO2 were used as materials to build the one-dimension (1D) defect photonic crystal and the medium of detect layer is Si. Using transfer matrix method, the optical transmission properties in 1D defect photonic crystals was analyzed, and the band gap property of 1D photonic crystal was obtained. Because of the defect, the defect peak appears in the transmission spectra. According to thermo-optical effect and thermal-expansion effect the optical depth and index of the materials and the defect of photonic crystal vary when the temperature changes. So the temperature can be measured by the wavelength shift value of the defect peak. Using 1D defect photonic crystal an experimentation system was set up for temperature measurement. The result showed that there is a linear relationship between the temperature of photonic crystal and the wave-length of the peak. And the sensitivity of this measuring system is 0207nm/℃ and the measurement range is -20—120℃.