A fiber optic sensing demodulation system based on a swept fiber laser was reported.A HCN gas cell was adopted as an embedded wavelength calibrator for the swept laser.The relation between the scanning voltage applied to the fiber Fabry-Perot tunable filter (FF-PTF) and the lasing wavelength was given out by a three order nonlinear fitting.The scanning voltage and multi-channel spectroscopy signal from sensors were sampled simultaneously and calibrated in real time.The interrogation wavelength resolution of 1.4pm and the long term repeatability of 3.2 pm were achieved.Demodulation test results for FBG and F-P sensors show that the system is capable of measuring the reflected peak wavelength of FBG and cavity length of fiber EFPI sensor with high accuracy.