Bisphthalonitrile (BPh) resin was modified by diallyl bisphenol A/bismaleimide resin prepolymer (DP/BMI). Differential scanning calorimeter (DSC) and Fourier transform infrared spectroscopy were used to characterize the curing acceleration of modified bisphthalonitrile (MBPh) resin. The results show that DP/BMI resin has a good acceleration effect on the curing of BPh resin, and the peak temperature of MBPh resin was 250.6 degrees C. MBPh resin was blended with novolac cyanate ester (NCE) resin, and DSC, rheometer, and thermogravimetric analyzer were used to investigate the curing reaction thermodynamics, rheological properties, and heat resistance of MBPh/NCE resin system. The results show that the addition of MBPh resin had little impact on the lowest viscosity (1-6 Pa s) of NCE resin. The DSC peak temperature of MBPh/NCE resin decreased to 235.7 degrees C after adding 30 wt% of MBPh resin. The addition of MBPh obviously increased the temperature at 90% carbon yield of NCE resin, with the 90% carbon yield temperature rising by nearly 100 degrees C. The mechanical properties of MBPh/NCE resin system were evaluated by tensile properties, bend properties, impact strength, and fracture toughness. The results show that MBPh had little impact on the tensile properties and bend properties of MBPh/NCE resin, and slightly increased their impact strength and fracture toughness.