A very low concentration of thermoplastic polybenzimidazole (PBI) film interleaved bismaleimide/diallyl bisphenol A (BMI/DBA) system with sandwich structure was designed for the outstanding impact resistance. The effects of PBI film layers (05) on the mechanical, thermal, dielectric properties and flame retardancy of BMI/ DBA were investigated. BMI/DBA interleaved with 5layer PBI film demonstrates a 274% increase in impact strength relative to BMI/DBA, and exhibits higher fracture toughness, flexural strength and modulus than BMI/ DBA. The improvement in the mechanical property for PBI film interleaved BMI/DBA system is mainly attributed to the combined effects of the effective energy dissipation of the sandwich structure and the good interfacial bonding between PBI film and the matrix. Due to the high thermal stability of PBI, the effective thermal insulation and electromagnetic field barrier of PBI film in the sandwich structure and the increase of the reacted C@C in resin system, PBI film interleaved BMI/DBA shows better thermal property, much higher flame retardancy and lower dielectric constant compared to BMI/DBA. In addition, when the same amount of PBI is applied, BMI/ DBA interleaved with PBI film exhibits much better comprehensive properties than BMI/DBA with PBI particles for the sandwich structure. POLYM. COMPOS., 00:000-000, 2017.