Based on the simulation theory and method, this paper establishes a status analogue simulation model in peak hours, realizes an effective assessment on the road, finds out bottlenecks to improve the level of road services and puts forward the corresponding road improvement program. This paper simulates the im- provement program by the use of VISSIM simulation model, and verifies the improvement effect of four pro- grams and carries out promotion. The research obtains an effective method of solving the problem of jam on the sub-arterial road: It needs to set up by-pass and control over traffic flow of the by-pass, and give full play to the role of by-pass in city.