To clarify theory of triboelectrical power generation over graphene membrane, we prepared several graphene samples having various number of layers on polytetrafluoroethylene substrate manufactured by the 3D printer equipment which can provide electrical parallel and series circuits of multi-graphene sheets. These properties of each graphene sample were characterized by Raman spectra, sheet resistance and water contact angle measurements. We demonstrated flow-induced power generation on graphene at various flow velocities and number of layers, respectively. The generated power for the monolayer graphene was 5.73, and 14.1 times larger than for 2 and 3 layers of graphene, respectively, based on the trioboelectrical phenomena at the thin membrane.