4-Nitro-4＇-amino-biphenyl (p-NBA), a photo- and thermostable chromophore with high nonlinear optical (NLO) activity, was used to react with various epoxy resins, then three linear functionalized epoxy polymers were obtained and further crosslinked with a trimer of hexamethylene diisocynate during poling process. The second harmonic generation behaviors of linear and crosslinked poled polymers have been investigated. The crosslinked epoxy polymer based on bisphenol-A with p-NBA moieties exhibits high NLO activity and stability.