A circuit board provided with double reinforcing layers and integrated double route circuits is characterized in that a first route circuit and a second router circuit are arranged in a penetrating opening and outside the penetrating opening of a first reinforcing layer and the second route circuit is provided with a series of perpendicular connection channels surrounding by a second reinforcing layer laterally. Circuit board bending can be avoided due to the mechanical strength of the first reinforcing layer and the mechanical strength of the second reinforcing layer. The perpendicular connection channels can provide electric connection points used for next stage connection. The first route circuit in the penetrating opening of the first reinforcing layer can provide a primary fan-out route while the second route circuit disposed outside the penetrating opening of the first reinforcing layer can provide further fan-out route for the first route circuit and also enables mechanical connection of the first route circuit and the first reinforcing layer.