Embodiments of the present invention provide a method for determining a management domain, and the method includes: receiving, by a second network device, a first packet sent by a first network device, where the first packet includes a domain ID of a first management domain and a first IP address set corresponding to the domain ID of the first management domain, and the first IP address set includes an IP address of a network device in the first management domain; and when the second network device determines that the first IP address set includes an IP address of the second network device, determining that the second network device belongs to the first management domain, and storing the domain ID of the first management domain. By using this method, it is unnecessary to manually configure management domain information on the second network device, thereby simplifying configuration of a virtual cluster.