The paper aims to develop an environmentally friendly biodegradable packaging material to promote green logistics and environmental protection. ECO biomass plate, a fully degradable biomass packaging filling material, was prepared by one-step in-situ molding technology. Its waterproofing, dynamic buffering, flame retardant and biodegradability were tested. The contact angle of ECO biomass plate was 104.2°; the buffer coefficient C was greater than 3.0; the oxygen index OI was more than 35. The samples were partially damaged after 20 days of burial, and degraded into small fragments and powders after 50 days. ECO biomass board prepared from agricultural and forestry wastes such as straw has good cushioning performance, can be waterproof and flame retardant, and is easy to be biodegraded. Compared with other degradable materials, it is a new type of cushioning packaging material with broad application prospects because of its low price, strong popularization and huge market competitiveness.