A one-dimensional (1D) pressure sensor based on defect layer has been studied by means of transfer matrix method, and the factors influencing the photonic crystal (PC) pressure sensor are analyzed. The effect of different doping ways and periodicity on transmitted light wavelength is simulated and researched by choosing small elastic modulus material as defect layer. The relation between the defect layer location and transmitted light is investigated by numeric analysis, and the calculations show that the intensity of transmitted light is greatest when the defect mode is located in the middle of the PC. The effects of periodical number of PC on the transmission are studied, and the results show that the transmission band becomes narrower with the increase of periodicity of PC, which is useful to the sensor. At the same time, when the periodicity increases to a certain number, if the periodicity is raised again, the transmission band does not almost change with the increase of periodicity of PC. On the other hand, if the transmission band becomes too narrow, the transmitted light intensity will be too weak to detect, which can affect the measurement of sensor. The relation between the thickness of defect layer and central wavelength is also studied. The change range of central wavelength will become larger with the increase of the thickness of defect layer, and the central wavelength of transmitted light will shift to long wave. When the width of defect mode is too large, the central wavelength of transmitted light can be together with cutoff wavelength, which can result in the transmitted light cutoff.