The invention provides an on-load regulated capacity transformer, and particularly relates to the field of power accessories. According to the on-load regulated capacity transformer provided by an embodiment of the invention, two ends of a common capacity-adjustable circuit transformer bank are connected to second circuit transformer banks in parallel; when the capacity is required to be adjusted, the second circuit transformer banks replace a first circuit transformer bank, or the first circuit transformer bank and the second circuit transformer banks bear load together; the first circuit transformer bank can also stop working thoroughly, when the capacity of the first circuit transformer bank is adjusted, the first circuit transformer bank can be shut down, the capacity of the first circuit transformer bank can be adjusted in a powerless environment or under the condition of small load, the specification of an on-load switch is not required to be limited, and the capacity can be adjusted via any mature on-load switches.