Objectives: For the important geological significance of alkali- rich intrusions, we studied the intrusions in north side of Yinshan Mountains and Yanshan Mountains on the petrogeochemistry and goechronology. Futhermore, we discussed petrogenesis and the magmatism evolution of these alkali- rich intrusions briefly. Methods: Our study is based on sample collection and field work, observe through a microscope and the data analysis of major elements, trace elements, and SHRIMP zircon U- Pb dating to get the high- precision ages of alkali- rich intrusions on the northern side of Yinshan Mountains and Yanshan Mountains. Results: The experimental data show that the SiO2 content of these whole intrusions account for 59.08%~66.52%, Al2O3=15.34%~21.67%, A/CNK<1, signifying that these alkali- rich intrusions belong to intermediate rock with quasi- aluminous. Geochemical characteristics of trace elements shows that the rocks enriches lithophile elements (LILE), such as Rb, Ba and Sr; on the contrast, it’s relatively poor in high field strength elements (HFSE), such as Ti, P, Nb and Ta. The rare earth elements geochemistry shows distact fractionation of LREE and HREE, reveals a deficit of heavy rare earth elements and enriched the light one; with strong negative Eu anomaly (δEu= 0.35~0.91). SHRIMP zircon U- Pb ages of Gucheng pyroxene syenite (G1- 2), hornblende syenite (G5- 1), hornblende syenite (G6- 1) are 414.6±5.0 Ma, 415.0±5.9 Ma and 413.2±3.3 Ma respectively；SHRIMP zircon U- Pb ages of Badaogou masanophyre and ivernite are 372.3±4.7 Ma and 366.8±5.2 Ma respectively. Conclusions: These alkali- rich intrusions we studied are all distributed in the northern margin of the North China Craton, according to the same characteristics of geochronology and geochemistry, there is an alkali- rich intrusions belt distributed in the East—West direction in the northern foot of Yinshan Mountains and Yanshan Mountains. From west to east, it is composed of five intrusions. The geochemical characteristics analyses indicates the magmas came from the mantle depth, relating to enriched mantle. And the magmas may be contaminated by crustal materials in the process of its ascending emplacement. It is speculated that the corresponding diagenetic temperature and the pressure depths of Huangheshao, Gucheng and Badaogou intrusions are roughly from the bottom to the middle of the thickend continental crust, and the formation depths of the Gaojiacun and Shuiquangou intrusions are deeper. The petrogeochemical discrimination based on the tectonic environment indicates that the Paleozoic alkali- rich intrusions belt in north side of Yinshan Mountains and Yanshan Mountains was mainly formed in the extensional tectonic environment and was the product of collision—postorogenic magmatism. Combined with previous studies on the Late Paleozoic tectonic and magmatism in the study area, it is concluded that the tectonic environment formed by the Paleozoic alkali- rich intrusions in Yinshan Mountains and the northern foot of Yanshan Mountains may be closely related to the extensional tectonic background after the arc—continent collision between the northern margin of the North China Craton and the Bainaimiao island arc on its northern side in the Late Paleozoic from Late Silurian to Early Devonian, it proves conclusion of tectonic environment discrimination further.