Object-level roadside perception provides strong support for intelligent and connected vehicles,which can promote the application of automated driving in the coordination system integrating vehicles,road infrastructures and clouds.However,sensors must be deployed properly to satisfy the requirements of detection coverage and deployment cost.In this paper,an optimization method of road network sensor deployment is proposed that decomposes the optimization problem in a road network into sub-problems on routes between intersections.The actual detection ranges are calculated under the influence of curve road geometry.A dynamic programming（DP） algorithm is proposed to optimize the multi-type sensor set deployment on each route for full detection area coverage and the minimum deployment cost To reduce the overlap of detection areas,a search-based adjustment algorithm is designed based on the proposed DP algorithm.Illustrative and comparative examples indicate that the proposed method is feasible and effective.