Abstract: In this paper,effects of peroxlde on curing reaction of modified BMI resin (designed as 4501A)with low dielectric loss were studied.Baslc components of 4501A are N,N'-blsmaleimidodiphenyl methane and allylphenyl compound.Tests,such as DSC analysis,gel characteristics of resin and propertles of neat resin show that the inltlator can strikingly reduce the curing temperature of resln.Propertles of both neat resin and composlte contalning initiator were all shown.Results indicated that the initiator has no effect on dielectric properties of neat resin but can greatly improve its heat distortion temperature.