The invention provides a method and a system for monitoring a virtual private network (VPN). The method comprises the steps of dividing services into different service levels according to service characteristics and the requirements of the services for network performance parameters; acquiring a comprehensive service quality value of each VLAN (Virtual Local Area Network) according to the network performance parameter and traffic data of a corresponding port of each service level; generating an initial polling priority table according to the comprehensive service quality value of each VLAN; and polling and monitoring each VLAN according to the initial polling priority table. The method and the system accurately realize real-time monitoring of the network condition, can utilize network resources more efficiently during VPN scheduling, reserve the security of the VPN technology, and solve the problem of difficulty in mass channel scheduling.