The invention relates to a photovoltaic array output voltage adjusting method and device. The photovoltaic array output voltage adjusting method comprises the following steps that: the output power ofa photovoltaic array at the current moment is compared with power required by a main network, and the adjustment voltage of the photovoltaic array at the current moment is determined according to a comparison result; and the output voltage of the photovoltaic array at the current moment is adjusted to be the adjustment voltage of the photovoltaic array at the current moment. According to the photovoltaic array output voltage adjusting method and device of the invention, when the adjustment voltage is determined under the condition that the output power of the photovoltaic array is greater than the power required by the main network, the photovoltaic array is classified according to illumination intensity; the total power of various photovoltaic modules is determined based on the power required by the main network; the specific environmental conditions of the different photovoltaic modules and the demand of the main network are considered, so that voltage adjustment performed when photovoltaic power is excessive is more accurate; and when the adjustment voltage is determined under the condition that the output power of the photovoltaic array is lower than or equal to the power required by the main network, a voltage correction parameter at the current moment is determined based on the historical voltage and voltage of the photovoltaic array, so that the photovoltaic array can perform output with the maximum voltage and provide electric energy for the main network.