Abstract: Observations of related strata in the North Qinling Mountains and recent regional geological surveys of the area indicate that a Devonian sea trough developed on the basis of the Caledonian fold belt in the North Qinling. It was connected with the Central Qinlng Devonian sea trough. By the end of the Devonian. the fold inversion began, forming a Yariscan fold belt, This paper furnishes grounds for the determination of this fold belt.