The Mai Son - National Highway 45 expressway has a length of 63.37 km, of which the section through Ninh Binh is 14.35 km long, and the section through Thanh Hoa is 49.02 km. The starting point is at the Mai Son junction, Yen Mo district, Ninh Binh province, connecting with the Cao Bo - Mai Son expressway and in the future is the Ninh Binh - Hai Phong expressway when completed. The end point connects with the Nghi Son - Tho Xuan road at Tan Phuc commune, Nong Cong district, Thanh Hoa province, continuing with the National Highway 45 - Nghi Son expressway.

Phase 1 of the project constructs a 4-lane road without an emergency lane (with some emergency stops), the road base is 17 m wide, the design speed is 80 km/h; the complete phase constructs according to the scale of 6 lanes, the road base is 32.25 m wide, the design speed is 120 km/h. On the route, there are two mountain tunnels, namely Tam Diep tunnel (245 m long) and Thung Thi tunnel (680 m long) designed with 6 lanes including two parallel tunnels. In addition, the Nui Do bridge crossing the Chu river on the route is also the longest river-crossing bridge in Thanh Hoa province to date.