AbstractIn order to increase the chemical bonding force between fiber and resin, several kinds of organometallic coupling agent (such as titanate, zirconate, and zircoaluminate) were chosen and added in the BMI resin formulation, which possess the same solvent system with those coupling agents. The DSC analysis technique was used to find the best curing condition, and TGA was used to investigate the thermal stability property of the best curing condition. For the purpose of analyzing the bonding structure, ESCA surface element analysis techniques was applied in this study. Beside that, the mechanical properties of tensile, flexural, and short‐beam shear strengths were measured for the effect of adding coupling agents, and the SEM of fracture surfaces were taken to study the fractural analysis. The results showed that composites with the application of organometallic coupling agents of [RO–Ti(OX–R′NH2)3] structure in the treatment of BMI resin were highly thermal stable. Also, it was shown that the mechanical strengths of composites fabricated by pretreatment of the carbon fibers with coupling agents were higher than those fabricated by adding coupling agents in resins, but there was no obvious improvement of mechanical properties with higher concentration of coupling agents. However, the SEM showed that the adhesion between fiber and resin can actually be improved by adding proper amount of coupling agents in the BMI resin formulation.