The invention discloses a bypass status cycle reporting method for power units and a topological structure. The bypass trigger circuit of each power unit is provided with the following ports: a bypasstrigger input signal port, a bypass contactor status signal output port reported to the power unit and a bypass contactor status signal output port reported to the adjacent power unit; and the unit control circuit of each power unit is provided with the following ports: an uplink optical fiber port from the unit control circuits to a main controller, a downlink optical fiber port from the main controller to the unit control circuits, a bypass trigger output signal port, a bypass contactor status signal input port of the power unit and a bypass contactor status signal optical fiber input portof the adjacent power unit. Thus, the cyclic interconnection of two or more power units can be realized through optical fibers, and when the uplink communication optical fibers from the power units toa control system are broken, the control system can judge the status of the bypass contactors of the power units through the adjacent power units.