Simultaneously improving the processability and heat resistance for bismaleimide (BMI) resins remains an open challenge. Herein, the processing performance of traditional BMIs with high melting points, including m-phenylene bismaleimide (MPD-BMI), 3,3'-diphenylsulfone bismaleimide (33DDS-BMI) and bisphenol A bismaleimide (BDM), is significantly improved by forming eutectic systems though blending with low-melting-point BMI monomers, indan bismaleimide (PIDA-BMI) and aliphatic bismaleimide trimethylhexane bismaleimide (SEM23). The results show that modification of the 33DDS-BMI system with PIDA-BMI yields a remarkable 60% reduction in melting point, coupled with a 6% increase in glass transition temperature (Tg), when compared to the unmodified 33DDS-BMI system. Similarly, compared with pure BDM, the SEM23/BDM system shows a 14% lower melting point, while its Tg and the flexural strength increases by13% and 10% respectively. Mechanistic analysis reveals that introducing low-melting-point BMI monomers forms a eutectic system, inducing amorphization of polycrystalline states via inherent structural differences in BMI monomers. This reduces resin crystallinity and enhances segmental mobility, thereby synergistically optimizing melting point, heat resistance, and mechanical properties. This work provides a strategy for simultaneously enhancing processability and heat resistance for BMI resins.