The invention relates to a graphene/polyamide acid all-solid-state supercapacitor and a preparation method thereof. According to the supercapacitor, reduced graphene oxide/polyamide acid gel is used as an electrode, and graphene oxide/polyamide acid gel is used as an electrolyte. The method comprises the steps of preparing a reduced graphene oxide/polyamic acid solution, preparing a graphene oxide/polyamic acid solution, preparing a reduced graphene oxide/polyamic acid gel electrode, preparing a graphene oxide/polyamic acid gel electrolyte and assembling the supercapacitor. The supercapacitorhas good energy storage performance. The method is simple and environment-friendly.