The present invention discloses a method and network device for detecting IP address conflict. The method for detecting IP address conflict comprises: collecting all the ARP entries from a broadcasting network segment; and carrying out a data check on the ARP entries collected, and determining that there is an IP address conflicted when it is detected that there are ARP entries with the same IP address but different media access control (MAC) addresses. The network device includes a collecting module and a detecting module. The present invention may achieve the function of IP address conflict detection in a broadcasting network segment by employing one or several network devices and uses the ARP flexibly. The outer appearance of the ARP protocol is not changed, and the other devices in the broadcast network segment do not need to modify the protocol or provide special function support.