The invention discloses an independent basic service set (IBSS) system and a power management method thereof. The method comprises the following steps: canceling the transmission of an ATIM (announcement traffic indication message) frame; if the node in IBSS does not have MSDU (MAC Server Data Unit) to send within each TBTT (target beacon transmission time), waiting for DIFS (distributed interframe space); if a beacon frame is not received during the period of DIFS, executing the processing procedure of a random delay timer; if the beacon frame is received during the period of DIFS, analyzing the traffic indication map (TIM) field of the received beacon frame; judging whether to receive MSDU based on the TIM field; and if the MSDU is to be received, keeping an active state; otherwise, turning to a sleep state. Through the technical scheme of the invention, the node energy is saved and the system efficiency is improved.