The objective of the present work was to develop a nonvolatile coating involving vinyl polar monomer and high performance maleimide-terminated polyimides (MTPs) with flexible backbone. The synthesized MTPs with different molecular weight (Mw) showed good solubility in N-vinylpyrrolidone (NVP), and the homogeneous binary systems were obtained even when the content of MTPs reached 50 wt%. NVP–MTPs copolymer resin were prepared by gamma ray initiated bulk copolymerization, followed by thermal postcuring to improve the properties. NVP–MTPs copolymer resins exhibited flexural strength higher than 76 MPa, glass transition ( T g) higher than 142 °C, thermal stability ( T 5%) no less than 214 °C, but relatively poor impact strength and water resistance property. It was revealed that increasing Mw of MTPs would result in the increase of impact strength and a decrease of thermal and flexural properties of copolymer resin, accompanied with the gradual decrease of gel percentage of copolymer resin. Amino-terminated linear polyimide (ATLP) was introduced to modify NVP–MTPs copolymer resin and the C–N linkage was formed from terminal NH 2 to electron deficient double bone on maleimide ring of MTPs via Michael nucleophilic addition. Polyvinylsiloxane (PVS) were introduced to modify NVP–MTPs copolymer resin by in situ ring opening polymerization followed with copolymerization under gamma ray initiation. The introduction of both modifiers led to an appreciable increase of impact strength and a remarkable water uptake decrease, meanwhile, other properties including thermal and flexural properties of modified copolymer resins maintained and even exhibited a slight increase. Fracture surface morphology by scanning electron microscopy (SEM) technique showed that introduction of both modifiers maintained good homogeneity of copolymer resin, and led to a gradual transition from rigid deformation to plastic deformation.