The invention discloses an ONU fault management method based on OLT and ONU mutual collaboration. The ONU fault management method comprises the following steps that step S1, a fault management Agent is additionally arranged on the master control panel of an OLT and an ONU; step S2, a management workstation acquires information reported by the OLT Agent and the ONU Agent; step S3, the management workstation judges existence of constant luminescence interference according to the preset rules and transmits the fault judgment result to the OLT Agent and the ONU Agent; and step S4, the OLT Agent and the ONU Agent take active and autonomous fault management according to the fault judgment result. The method is used for substituting the manual fault diagnosis method so that the fault diagnosis efficiency can be enhanced.