The fault detection technique for the wavelength division multiplexing passive optical network (WDM-PON) is proposed based on an erbium-doped fiber amplified spontaneons emission (ASE) source. It is quite difficult to the link fault detection because of the multi-branch and node density structure of WDM-PON. The technology utilizes the broadband characteristics of the erbium-doped fiber ASE source with the double-pass backward configuration and the delta correlation properties of the time-domain output. It can solve the problem in the WDM-PON fault detection of fiber links. In the experiments, the detection of 8 channels WDM-PON can accurately locate the fiber breakpoint, the joint looseness, and multi-fault reflection. The results show that the 23 dB dynamic range and 4 cm spatial resolution which is independent to the measuring distance are realized. The technology is able to achieve the detection of the WDM-PON faults with 32 channels based on the broadband characteristics of the ASE source to realize WDM-PON fiber link fault location with centimeter resolution.