The invention provides a method for controlling transmission priority, a system, a device and user network edge equipment thereof, wherein, the method comprises: one or a plurality of pieces of equipment in multi-protocol label switching (MPLS) core network is collocated with the corresponding relation between routing information and quality of service (QoS) in advance; when the equipment confirms that certain routing information satisfies the condition for releasing QoS information, the QoS information of the routing information is obtained from the corresponding relation, and the routing information and the QoS information of the routing information are forwarded by hop-to-hop to the user network edge (CE equipment) in the user network; the CE equipment receives the routing information and the QoS information of the routing information, when the routing information is used for transmitting the service flow, the IP message head of the service flow carries the IP priority information which the QoS information is corresponding to. The invention leads to simpler collocation and maintenance work and lowers the cost of the collocation and maintenance work.