To investigate the combined effect of graphene (Gra) and poly(methoxy poly(ethylene glycol) monomethacrylate-co-1-vinyl-3-ethylimidazolium bromide) (P[MPEGMA-IL]) on morphology, crystallization behavior and dielectric properties for polylactide (PLA)/poly(e-caprolactone) (PCL) blends, a series of PLA/PCL blend based composites have been prepared using solution-cast method. P[MPEGMA-IL] modified Gra could mainly localize in PCL domains, and improved the dispersibility of PCL phase in the composites. Due to the heterogeneous nucleation of Gra and ion cluster of P[MPEGMA-IL], the crystallinity of PLA and PCL were improved simultaneously with the increase of modified Gra content. The good conductivity of Gra and the better dispersion of PCL made the PLA/PCL blends higher dielectric permittivity owing to the increase of the mobile charge carriers at the interfaces.