The invention relates to an adjustment method for removing main transformer-crossing reactive circular power flow of a photovoltaic power station, and belongs to the technical field of reactive automatic adjustment of voltage of the photovoltaic power station. The method comprises the steps as follows: current reactive power values of all low voltage sides of main transformers and SVGs can be obtained from a local monitoring system of the photovoltaic power station; the reactive power sum that the current reactive power values of all low voltage sides are greater than 0 and the reactive power sum that the current reactive power values of all low voltage sides are less than 0 are respectively counted; whether the phenomenon that the main transformer-crossing reactive circular power flow exists in various main transformers or not is judged according to the two reactive sums and opposite signs or same signs; whether the reactive power flowing into the main transformers or the reactive power flowing outside the main transformers is removed firstly is determined according to the absolute values of the two reactive power sums; the reactive power set value of each SVG is determined according to the total reactive power quantity of the removed circular flow; and the reactive power set values of the SVGs are corrected according to the adjusting step lengths of the SVGs. According to the method provided by the invention, the phenomenon of the main transformer-crossing reactive circular power flow of the photovoltaic power station can be timely removed when appearing; and the economical efficiency of main transformer operation of the photovoltaic power station is improved.