A geometrical model, which utilizes an assemblage of parameters of propagation anticline to constraint the depth and geometry of the blind detachment fault, is figured in this paper based on both balanced geosection principles and previous studies. The parameters measured from anticline in this model include backlimbangle, interlimb angle, the height of anticline, the width of the anticline and the thickness of the layer upwards point fault tip. The calculation could be practiced using software ZB1.0, which was programmed in VC++, and gives results of the detachment fault, including ramp dip angle, fault-parallel distance, strata draught and the deepth of fiat. Parameters of anticline, which are from seismic and geological sections of the Cizhuya propagation anticline, respectively, give the consistent depth and dip angle of detachment fault at 8.10 ~