The invention provides a network asset information collection and monitoring system, and belongs to the field of network security. The method comprises the following steps: performing sub-domain nameblasting on a main domain name to obtain a sub-domain name set; further, obtaining all network asset information corresponding to all IP addresses through ipwhois and port scanning; and classifying all IP addresses and all domain names, comparing all network information acquired by the IP addresses with open services with all network asset information acquired by the IP address of the master station, taking multiple values, classifying and inputting the multiple values into a useful network asset information list of the to-be-checked enterprise, and completely inputting other types of classifications. Middleware scanning is performed on a useful network asset information list, a vulnerability list corresponding to middleware information is pulled, and a vulnerability alarm is given. According to the invention, the classified network asset information in units of enterprises can be obtained through simple main domain name input, the network assets are subjected to security monitoring, the steps are simplified, and the method is simple and easy to implement.