Three different formulas with low-cost resins, made up of N,N'-bismaleim- idephenylmethane (BMI), O,O'-diallybisphenol A(BA), and N-phenylmaleimide (NPMI) were developed. The properties of prepolymers, such as activation energies, enthalpy, and constants of reaction rate, were obtained by a kinetic programmer on DSC. Thermal and mechanical properties of neat resins were also studied. The results showed that the systems had low melting point and low viscosity. All cured resins presented excellent thermal and good mechanical properties. The mechanical properties could be affected by the quantity of NPMI and postcuring process. The water absorption is less than or equal to1.98%; heat deflection temperature (HDT) is greater than or equal to 250 degreesC after aging for 100 h in distilled water of 90 degreesC. The data indicate that the BMI can be effectively improved by adding BA and NPMI, while its heat resistance and hot/wet mechanical properties can be fairly retained.