In order to satisfy the requirement of high precision optical fiber fault diagnosis, we have developed a chaotic light source module, which is composed of a bandwidth chaotic signal source and a laser modulation circuit. Among them, the bandwidth chaotic signal source produces a chaotic electrical signal with flat frequency spectrum and 10 dB bandwidth up to 500 MHz. When the signal is amplified by the modulation circuit, the driving distributed feedback (DFB) semiconductor laser can output high power and broadband chaotic laser signal. When the chaotic source module is applied in optical fiber fault diagnosis, it can not only realize the detection of fiber breakpoints and mismatch junctions, but also achieve a range-independent spatial resolution of 0.35 m in the detection range of approximately 107 km. In addition, the chaotic source module can be conveniently applied to such fields as chaotic radar and chaotic secure communications.