Based on the study and combined with the interpretation of the gravity and magnetic anomalies of the basement of the study region, the authors propose that there is a regional detachment layer formed in the middle crust in the North China Block, and its depth determines the transition between the shallow and deep deformation in the study region. The detachment layer is the floor boundary of the deformation during the extension of the North China Block. When units of upper crust of the region slip along the detachment layer, owing to different velocities and boundary conditions, the derived cut-off lines, transverse faults and minor related highs and depressions are formed, all these are the basal tectonic units consisting of the upper crust of the North China Block, and they controlled the distribution of the basins and ranges and tectonic landforms basically in the study region.