Abstract: Phenyl vinyl compounds(styrene and divinyl styrene) modified bisphenol A dicyanate ester resin (BADCy) has been studied in this paper. The composition of the resin matrix has been selected according to a triangular optimization method as well as the experiment result. The phase separation of modified resin matrix at temperatures below 40℃ has been resolved by adding a little molecule substance containing oxygen atoms. At the same time, the storage stability has been prolongated efficiently. The modified resin system is suitable for RTM process at room temperature.