Adynamic user-optimal link-based variational inequality assignment model in saturated urban traffic network is proposed. The flow is assigned to network accord the boundary-optimal principle. The flow propagation constraint, First-in-first-out constraint, link capacity constraint and the physical queue are considered. The link travel time experienced by vehicles in saturated network is dealt with two components: the uncongested cruise time over the link and the queuing delay. Finally, a discrete model and its nested diagonalization algorithm were given. An example was used to test the necessity and validity of the modeling.