To obtain attractive properties, such as increased resistance to moisture absorption, low dielectric constant and low dielectric loss, the novel bismaleimide, viz. 2,7-bis(4-maleimidophenoxy) naphthalene (BMPN), and dicyanate ester, viz. 2,7-dihydroxynaphthalene dicyanate (DNCY), containing naphthalene ring and ether linkages, have been synthesized. The cure process of the blends including of 0.11mmol/mol Fe(AcAc)3 and 2% nonylphenol is characterized by in-situ FTIR. The result obtained from in-situ FTIR spectra of cured resin illuminates that the cure reaction is homo-polymerized respectively at this condition for the mixtures of B1C1. Interlaced network patterns are seen obviously and no visible phase separation could be detected in the region for IPNs BT resin by SEM. The structure of IPNs can be formed for the blends of BMPN and DNCY containing 0.11 mmol/mol Fe(AcAc)3 and 2% nonylphenol, which is tested by in-situ FTIR and SEM methods. The glass fiber reinforced composites for this blends are made and their properties are studied. This composites show good flexural property, low dielectric constants ( Dk ) and low moisture absorption.