With the rapid development of Hefei's urban scale and the rapid increase of traffic flow, the construction of viaducts between the old and new urban areas has played a better role in alleviating urban road congestion. However, the off-ramp of viaduct, like most viaducts, still cannot avoid congestion. Based on the investigation of some typical viaducts such as Jinzhai Road in Hefei city, this paper expounds the advantages and disadvantages of viaduct in urban construction through related analysis, research and program prediction, and summarizes the causes and types of viaduct congestion. Aiming at solving off-ramp of viaduct congestion in Hefei, this paper puts forward some feasible measures, such as strengthening the comprehensive control of viaducts, optimizing road resources and improving off-ramp setting conditions, so as to alleviate the traffic congestion of existing viaducts in Hefei and to avoid similar problems in the construction of new viaducts.