The invention discloses a method for discovering key person in a dynamic large-scale social network, which belongs to the field of data mining and social network analysis. The method first performs node labeling and parameter K selection, and then calculates the mutual influence between the nodes in a certain localized network. The importance index of the single node is calculated and the key person is found according to the task type. The method for discovering key person in a dynamic large-scale social network puts forward a concept of universal influence, and gives a formula of calculating the mutual influence between the nodes in a certain localized network and the importance index, and has advantages in the large-scale dynamic social network. According to the difference of the task type, the method can have different result processing strategies, and can adjust the parameter K to balance the time complexity and accuracy.