A wavelength demodulated method of fiber Bragg grating (FBG) is proposed to measuring human temperature and heart sound, which can achieve distributed static wavelength demodulation of multi-FBGs and dynamic wavelength demodulation for single FBG. The relation between control voltage of Fabry-Perot (F-P) filter and its output wavelength is rectified by pectinate filter, so the precision of static demodulation is improved. By adding dithering signal the center wavelength of F-P filter could be remained on work point so that it could demodulate dynamic wavelength for a long time. The experiment results indicate that the precision of static wavelength demodulation is ±5 pm and the repeated error is about 5 pm. The theoretical dynamic demodulated range is 225 pm and the actual range is about 203 pm. The theory bandwidth of 3 dB of system frequency response is 1 kHz and the measured value is about 950 Hz. In the heart sound concentrated band of 20~200 Hz, frequency response are basically the same.