The invention relates to a video conference access QoS (Quality of Service) assurance method based on an IMS network. The video conference access QoS assurance method comprises the following steps: an upper architecture is set up; a QoS level re-positioning functional module is newly increased in the upper architecture; with the help of a parameter, namely a service flexibility bit, different priority levels are set for different services including voice, videos and data in a video conference by utilization of the module; a lower architecture aggregates priority level information of the upper architecture through a multi-protocol label switching network, maps the priority level information into different labels, and performs data forwarding according to the labels; and the upper and lower architectures are mutually connected into a whole, so that a MPLS-based IMS network QoS overall architecture is obtained. The video conference access QoS assurance method disclosed by the invention has the advantages that: a PCC architecture in an original IMS is improved; therefore, flexible and dynamic QoS assurance can be realized; simultaneously, network resources are optimized; effective bearing is realized through a MPLS technology; the packet forwarding rate is increased; and the QoS is ensured.