The invention provides an inverter system and an inverter over-capacity-distribution control method. The inverter over-capacity-distribution control method includes the following steps that: the direct current-side voltage and alternating current-side output power of an inverter are calculated, whether the direct current-side voltage and the alternating current-side output power satisfy a high-voltage full-load operating condition is judged; the direct current-side voltage and alternating current-side output power of the inverter satisfy the high-voltage full-load operating condition, at last one switching device at a direct current side is controlled to be turned off, so that the input power of a photovoltaic array can be decreased, the direct current-side voltage of the inverter is made to be decreased through maximum power point tracking control under a condition that the alternating current-side output of the inverter is allowed maximum power; and operation is performed continuously until the direct current-side voltage of the inverter drops to a preset threshold value. With the inverter over-capacity-distribution control method adopted, the maximum power output of the inverter can be ensured, and the working point direct-current voltage of the inverter is decreased. According to the prior art, when the output power of the photovoltaic array is larger than maximum power which can be outputted by the inverter, the working point direct-current voltage will be too high, and as a result, the service life of the inverter will be affected, the operating reliability of a system will be decreased, and the generated power amount of the system will be decreased, while, with the method of the invention adopted, the problems in the prior art can be solved.