The invention belongs to the field of single-phase 
photovoltaic power generation, and discloses a single-phase photovoltaic grid-connected generating 
system power decoupling circuit and a control method thereof. The circuit comprises a photovoltaic power supply, a BOOST unit, a full-bridge inverting unit, a power decoupling unit, an LC filtering unit and a 
power grid, which are sequentially connected from left to right. The method comprises the following steps of: (1) boosting the 
voltage of the photovoltaic power supply through the BOOST unit; (2) inverting the direct-
current voltage boosted in the step (1) into an alternating-
current voltage through the full-bridge inverting unit; (3) generating a 
power vector on an 
inductor Lc by controlling the switch-on / 
off time sequences of 
MOSFET (
Metal-
Oxide -
Semiconductor Field Effect Transistor) switching tubes Sc1and Sc2 in the power decoupling unit by using the power decoupling unit; and (4) filtering an alternating-current grid connected 
voltage signal output from the step (3) through the LC filtering unit, and connecting the 
signal into the 
power grid. Due to the adoption of the circuit and the control method thereof, a low-capacity 
film capacitor is adopted instead of a high-capacity 
electrolytic capacitor, so that the generating efficiency of a 
photovoltaic system in increased, the service life of the 
photovoltaic system is prolonged, and generating cost is effectively lowered.