The influence of the components of a modified bismaleimide (BMI) resin on the thermal properties and impact properties of these resins are investigated in this paper. Toughened BMI resin castings incorporating 0%, 5%, 10%, 15%, 20%, 30%, and 40% (by weight) thermoplastic-modified polyetherketone (PEK-C) were prepared. The modified resins were characterized and analysed using dynamic mechanical thermal analysis (DMTA), thermogravimetric (TG) analysis, free beam impact tests, and scanning electron microscope (SEM) techniques. The results indicate that a typical 4,4＇-bismaleimidodiphenyl methane (MBMI)/0,0＇-diallybisphenol A (DABPA) two-component system modified with 4,4＇-bismaleimide diphenyl ether of biphenyl A (MEBMI), Allyl phenol epoxy (AE), and PEK-C has a high glass transition temperature (Tg), excellent thermal stability, and outstanding impact strength. This novel toughened BMI resin is expected to find use in advanced composites.