The invention discloses a method used for processing heavy metal wastewater with a tea saponin-reduced graphene oxide composite material. The method comprises following steps: the tea saponin-reduced graphene oxide composite material is added into heavy metal wastewater, an obtained mixture is subjected to oscillation in a constant temperature water-bath kettle for 1 to 2h at 20 to 30 DEG C, wherein oscillation speed is controlled to be 170 to 190rpm. According to the method, the tea saponin-reduced graphene oxide composite material is obtained via absorption of tea saponin on the surface of reduced graphene oxide, and the tea saponin-reduced graphene oxide composite material is of a stratified porous nano structure obtained via combination of tea saponin with reduced graphene oxide via chemical bonds, wherein the surface of the stratified porous nano structure is smooth. The method is excellent in processing effect, no secondary pollution is caused in absorption process, and solid liquid separation is convenient to realize.