The invention discloses a plant straw novel lightweight wall body material. The plant straw novel lightweight wall body material is prepared by the following raw materials in parts by weight: 40-50 parts of fly ash, 20-30 parts of modified plant straw powder, 20-30 parts of sulphate aluminium cement, 10-20 parts of expanded perlite, 10-15 parts of silica powder, 10-15 parts of modified clay, 10-20 parts of glass fiber, 2-4 parts of foaming agent and 3-6 parts of water reducing agent. The plant straw novel lightweight wall body material disclosed by the invention is manufactured by utilizing an industrial waste material, namely the fly ash which is produced by abundant local coal mine resources and an agricultural waste, namely plant straw, so that the phenomena of disordered arrangement and disordered placement of the fly ash, excessive burning of the plant straw and the like can be effectively prevented, a natural environment can be protected, the production cost can be simultaneously greatly reduced, the cyclic utilization of the solid waste is realized and the energy-saving requirements of buildings can be also met. The produced wall body material has the advantages of higher compressive strength, smaller contractibility, light weight, heat preservation, heat insulation, sound insulation, fire resistance and the like.