A novel method of Er-doped optical fiber (EDF) dual-wavelength Raman hybrid amplification for fiber Bragg grating (FBG) sensor system based on swept laser is proposed for achieving ultra-long distance quasi-distributed measurement. Such a method employs a high power swept laser as the light source. Dual-wavelength Raman fiber amplification is adopted to achieve low-noise bidirectional amplification of FBG signals, and two sections of EDFs arranged along the fiber link remotely are used for generation of amplified spontaneous emission (ASE) light to illuminate remotely-located FBG sensors and also amplification of sensor signals with the residual Raman pump power, making the whole sensor system capable of obtaining reasonably good signal-noise-ratio (SNR) for an ultra-long distance. The experimental results show that an optical SNR of ～7 dB has been achieved for a 100 km transmission distance with a swept laser, a low Raman pump power of ～170 mW at wavelength of 1455 nm and a Raman pump power of ～2 W at wavelength of 1480 nm, which leads to realization of FBG-based sensing along ultra-long distance.