The embodiment of the invention provides a global maximum power point determining method and tracking method for a photovoltaic system. The tracking method comprises the following steps: acquiring a highest local peak point in a power voltage curve of the preset photovoltaic system, namely, a photovoltaic array formed by photovoltaic cell monomers made of the same material; obtaining a power per unit value corresponding to the highest local peak point according to the photovoltaic array and the highest local peak point, wherein the power per unit value includes parameters of the position of the highest local peak point and the number of the local peak points; and determining a global maximum power point of the preset photovoltaic system based on the power per unit value of the highest local peak point. According to the method, the local peak point of the power voltage curve is acquired, the power per unit value of the local peak point is solved, the local highest peak point is found from the local peak points to determine the global maximum power point in the photovoltaic system, the process of acquiring the global maximum power point is simplified by combining formula calculation,and the photovoltaic global maximum power tracking speed is improved.