The invention discloses a power equilibrium control method for reducing DC voltage fluctuation of a cascaded H-bridge inverter, and aims to solve the problem that power generation quantity is reduced caused by relatively large DC-side voltage fluctuation. The power equilibrium control method comprises the following steps of controlling a total DC-side voltage to achieve tracking of a maximum power point voltage of the DC-side voltage of each H-bridge unit and obtain an active current instruction value of a system; controlling decoupling of a network-side current, where independent control on an active current and reactive current can be achieved, and meanwhile, a total modulation wave voltage of the inverter is generated; and performing power equilibrium control between units, an accurate on-off state of each H-bridge unit is determined and power equilibrium control of each H-bridge unit and maximum power tracking of each H-bridge unit are achieved by sequencing an error of the DC-side voltage of each H-bridge unit. By the method, various working conditions can be adapted, stable running of the cascaded H-bridge photovoltaic inverter within a relatively large range can be achieved, moreover, the DC-side voltage fluctuation can be reduced, and the power generation quantity of the system is improved.