In order to better understand the principle of optic fiber sensing,an d to improve various aspects of performance of the optical fiber sensor for the temperature,a novel optic fiber temperature sensor based on double-demodulation of the wavelength and intensity is presente d.A 30mm polarization maintaining fiber (PMF) is spliced with lumbar enlarge between two conventional single-mode fibers (SMFs) to construct an all fiber M-Z sensor.The phase diffe rence between the cladding and core regions is changed with the external temperature increases,and then th e interference spectrum is changed.The light source is a broadband super luminescent light-emitting di ode (SLED) with wavelength range from 1450nm to 1650nm. The spectrum is measured by an optical spectrum analyzer (OSA) with a resolution of 20pm.The temperature is from 25℃ to 75℃.The results show that the wavelength has a red shift and intensity is gradually enlarged with temperature increases.Therefo re,the sensor uses the method of the wavelength and intensity for temperature measurement,and the sens itivities of the sensor are 0.127nm/℃ and 0.32dB/℃,respectively,corresponding to the resolutions of 0.16℃ and 0.03℃.The sensor has the advantages of simple manufacture,low cost,structural stability and high resolution,so it can be applied to the actual measurement.