Abstract: Disclosed in the present invention are a nitrogen-containing heterocyclic compound, and a preparation method therefor, an intermediate thereof, and an application thereof. The present invention provides a nitrogen-containing heterocyclic compound as represented by formula (I), a stereoisomer thereof, or a pharmaceutically acceptable salt thereof. The nitrogen-containing heterocyclic compound as represented by formula (I), the stereoisomer thereof, or the pharmaceutically acceptable salt thereof provided by the present invention has the activity of inhibiting proliferation of Ba/F3 KRAS-G12D cells, AGS cells, Ba/F3 KRAS-G12V cells expressing KRAS G12D and/or KRAS G12V mutant proteins, and also shows good in vivo tumor suppression activity; the present invention is expected to treat and/or prevent a variety of diseases mediated by KRAS G12D and/or KRAS G12V.