The granitoids in Yunmengshan area, located on the northern margin of the North China Craton, are important for understanding the formation time and mechanism of the tectonic background transition in this area. In this paper, the authors present zircon SHRIMP U-Pb ages and geochemical characteristics of the granitoids in Changyuan pluton, Guanshan pluton and Yunmengshan pluton. The results, in combination with available zircon U-Pb ages, show two magmatic periods in Yunmengshan area:162~151 Ma and 151~141 Ma. Compared with the second period, samples from the first magmatism period are higher in Mg^# but lower in SiO₂, which indicates that they evolved from the mantle source to the crust source during Late Jurassic-Early Cretaceous compression episode, accompanied by crustal thickening, even with some exposed moderately-fractionated granitoids. The transition from compression to extension in the study area lasted for 12 Ma, i.e., from 141 Ma to 129 Ma. The granitoids from Yunmengshan area were formed in a compressional environment before decratonization, and the thickened crust possessed the condition for later delamination.