Multi-terminal electric-double-layer transistors have recently attracted extensive interest in terms of mimicking syn-aptic and neural functions.In this work,an Ion-Gel gated graphene synaptic transistor was proposed to mimic the essential syn-aptic behaviors by exploiting the bipolar property of graphene and the ionic conductivity of Ion-Gel.The Ion-Gel dielectrics were deposited onto the graphene film by the spin coating process.We consider the top gate and graphene channel as a pre-synaptic and postsynaptic terminal,respectively.Basic synaptic functions were successfully mimicked,including the excitatory postsynaptic current(EPSC),the effect of spike amplitude and duration on EPSC,and paired-pulse facilitation(PPF).This work may facilitate the application of graphene synaptic transistors in flexible electronics.