Abstract: Balanced-section technique is a forward-inversion method of geologic section. which is based on geometric conservation principle. It is an importantmeans for the recovery of structural deformation.During study, usingGeosec technique tomake balanced sections of the 9 seismic lines and calculate the amountof extension and contraction of the for layer. The results show that
Yanqi basin is inweakly compressive status in earlyYanshanian with smaller amount of structural deformation. While main deformation is concentrated in lateYanshanian and Xishanian, but the deformation isweaker inXishanian than that inYanshanian.on the plane, deformation is stronger inwest than that in the east of the basin, mesozoic-cenozoic evolution of the basin is divided
into 3 stage, such as weak compression and syn-deformation stage in earlyYanshanian, strong compression stage in lateYanshanian and face compression stage in Xishanian.

Key words: balanced-section, structural-evolution, structural-deformation, Yanqi-basin