The invention provides a distributive photovoltaic grid-connection node weakness index prediction method. The method comprises the following steps of: establishing a time sequence of a distributive photovoltaic grid-connection node weakness index evolution system, processing time sequence measured data by virtue of an inertial weight particle swarm method, then predicting and calculating the weakness index of the distributive photovoltaic grid-connection node, and obtaining a predicted value of the photovoltaic grid-connection node weakness index. By adopting the method, the weakness of the local power grid photovoltaic grid-connection node can be predicted and calculated according to monitored parameters, a voltage level is controlled in real time according to a calculation result, the imbalance phenomenon of the voltage level among various photovoltaic systems can be effectively avoided, and the reliability and economical efficiency of the local power system can be remarkably improved.