By exploiting the low reflectivity of low-Bragg-reflective fiber grating, the distributed optical fiber sensing scheme based on identical-low-Bragg-reflective fiber gratings is proposed, theoretically analyzed and experimentally studied. The demodulation technology named "optical wavelength time-domain reflection", which utilizes the optical power variation of reflected sensing signal in both time domain and wavelength domain, is adopted. The influence of reflectivity of fiber grating, interval between adjacent gratings and transmission loss of delay fiber on the multiplexing capacity of the sensing system are also discussed. Results demonstrate that this sensing scheme can increase the multiplexing capacity of sensing system effectively, implement multi-point measurement and reduce the cost of signal demodulation. Experiments on this scheme are conducted to prove its feasibility. Four fiber Bragg gratings (FBG) with the reflectivity of 6% are multiplexed in this system, which agrees with the calculation result. The resolution of 0.12 ℃ for temperature measurement is obtained.