An anti-collision method and system in a wireless network system are provided. The anti-collision method includes: transmitting a beacon signal including information related to an owner type of a first device and information related to an available time interval of the first device; transmitting information related to a time interval selected from the available time interval to a second device having receiving the beacon signal from the first device; and updating the information related to the available time interval using information related to the selected time interval. The information related to the owner type of the first device includes information indicating one of a unicast device and a multicast device.