The invention relates to a method for confirming the time of multicast/broadcast MBMS service, wherein said method comprises: when user terminal adds and leaves MBMS service, network controller sendsmessage with user terminal mark and MBMS service mark to the broadcast multicast service center BM-SC; BM-SC based on received message confirms the times that user terminal adds and leaves the servicemark, and uses the time difference as the MBMS service time. The invention also discloses a relative system, which comprises user terminal, network controller, and BM-SC.