From the angle of the transmission spectrum of long period fiber grating (LPFG) and the wavelength interrogation technology for fiber Bragg gratings (FBGs), the edged filter characteristic of LPFGs is studied. A double-edged filter wavelength interrogation technology for FBGs is proposed. The theoretical model is deduced and the experiments of temperature and vibration signal monitoring are verified. The demodulation system, which is repeatedly tested under the excitation frequency of 580, 1000 Hz and 2500 Hz, respectively, shows broad dynamic frequency band of 3 kHz, fast response time and high accuracy, with the extensive application prospects.