Polyimide (PI) is a polymer having a rigid aromatic chain as a basic structure with excellent electrical properties such as electrical insulation and low dielectric constant as well as excellent thermal and chemical properties, and is widely used in various industrial fields. In order to improve the properties of the PI, the crosslinking of PI with end-capping using ethylenyl group was investigated. In our study, we could obtained crosslinked PI via chemical crosslinking using multi-functional amine moieties. Crosslinked PI film were synthesized from 4,4’-oxydianiline (ODA), benzene-1,2,4,5-tetracarboxylic dianhydride (PMDA) and 1,3,5-tris(4-aminophenyl)benzene or N,N,N’N’-tetrakis(4-aminophenyl)1,4-benzenediamine. Poly(amic acid) (PAA) was synthesized in proportions of 0, 1, 3 and 5wt%, and PI film was prepared by thermal imidization. The thermal properties of the film were measured using a thermogravimetric analyzer (TGA), the mechanical properties were confirmed using a universal test machine (UTM), and the surface of the film was observed with a scanning electron microscope (SEM) respectively.