Two kinds of polymer blends, Polyamide 11(PA11)/Styrene maleic anhydride (SMA) and Polyamide 11/Ethylene vinyl acetate-g-maleic anhydride (EVA-g-MAH), were prepared to study PA11 component crystallization in them. PA11/SMA blends were employed to characterize the in-situ reaction between anhydride group and amine termination of PA11. FT-IR and Solid-state C NMR indicate that PA11-g-SMA graft polymer was in-situ formed at the interface during polymer blending process. DSC measurements show that SMA and EVA-g-MAH decrease the crystallinity and melting point of PA11 component. WAXD illustrates that PA11 crystalline transit from the original δ′ form to α form in the blends. The in-situ reactant also leads to decreased glass transition temperature substantiated by DMA measurements. These graft copolymers are expected to impede the effective packing of PA11 molecules to form crystal as well as changing the crystal pattern way.