The　Kevlar　fiber,　treated　with　toluene-2,4-diisocyanate　and　caprolactam,　was　used　to　reinforce　MC　nylon　6.　XPS　showed　the　change　in　chemical　components　and　spectra　after　fiber　was　treated.　IR　showed　that　the　spectra　of　Kevlar　fiber　and　MC-nylon　6　were　incorporated　purely　when　they　were　mixed,　while　the　treated　KevIar　fiber　provided　the　activation　in　the　ring-opening　polymerization　of　caprolactam,　and　the　amide　groups　of　graft　chains　could　form　strong　hydrogen　bonds　with　matrix.　These　graft　chains　and　hydrogen　bonds　would　contribute　to　improving　interfacial　bonding　between　MC-nylon　6　and　Kevlar　fiber.　XRD　indicated　that　the　induction　of　Kevlar　fiber　had　no　effect　on　the　cryastalline　style　of　MC-nylon　6　obviously,　however,　the　crystals　had　better　seasonal　structure.　The　crystals　of　MC-nylon　6/Kevlar　fiber　composites　were　more　perfect　than　that　of　MC-nylon　6/Kevlar　untreated　fiber　composites　with　the　same　amount　of　Kevlar　fiber.　The　increase　of　Kevlar　fiber　contributed　to　forming　perfect　a　spherulite　when　the　mass　concentration　of　Kevlar　fiber　was　less　than　2%,　however,　the　more　the　Kevlar　fiber,　the　less　the　content　of　a　spherulite　when　the　mass　concentration　of　Kevlar　fiber　was　more　than　2%.