In order to ensure the safe and stable operation of the power system after large-scale grid-connection of new energy, it is necessary to quantitatively assess the vulnerability of the power grid before and after grid-connection. Therefore, a composite new energy power grid vulnerability analysis method based on complex networks and electrical characteristics was proposed, and the IEEE-39 node was simulated. Firstly, a vulnerability assessment system was constructed by selecting degree centrality, proximity centrality, eigenvector centrality, electric power flow interval, voltage stability and power balance, and then solving each secondary index according to the formula. Secondly, entropy weight method was used to calculate the index weight, TOPSIS method was used to rank the vulnerability of nodes before and after grid connection, and comparative analysis was made. Finally, the obstacle factor model was used to analyze the influence degree of each index on the vulnerability of power grid. The research results indicate that the number and location of new energy sources connected to the grid affect the vulnerability of the power grid. Among the influencing factors of grid vulnerability, the order of influence is voltage stability indicator > closeness centrality indicator > active power balance indicator.