A novel kind of high performance composite of nano-Si3N4/epoxidized silane/cyanate ester (nano-Si3N4/ESi/BCE) has been developed. The mechanical, thermal and dielectric properties of the composite were investigated. The impact and flexural strength values of the nano-Si3N4/ESi/BCE system are 15.7 kJ/m(2) and 114.2 MPa, respectively, which are increased by about 56 and 21 % compared with those of pure BCE resin, respectively. The glass transition temperature of the nano-Si3N4/ESi/BCE system is 278.7 A degrees C, which is nearly 30 A degrees C higher than that of pure BCE resin. In addition, nano-Si3N4/ESi/BCE system also exhibits lower and more stable dielectric loss than pure BCE resin over the testing frequency from 10 to 50 MHz. All these improvements of properties are closely correlated to the synergistic effects between nano-Si3N4 and ESi in the BCE matrix. The novel nano-Si3N4/ESi/BCE system with the outstanding integrated properties shows great potentialities to be applied in the field of electronic packaging.