The invention provides a polyvinyl alcohol-acorn starch-gulcomannan composite material and a preparation method thereof. The polyvinyl alcohol-acorn starch-gulcomannan composite material comprises, by weight, 36-48 parts of polyvinyl alcohol, 15-25 parts of acorn starch, 8-16 parts of gulcomannan, 2-5 parts of quaternary ammonium salt, 2-5 parts of talc, 1-3 parts of aluminum oxide, 1-2 parts of saccharin and 1-2 parts of plasticizer. The preparation method comprises the steps that (1) the raw materials except the polyvinyl alcohol are added into water, heating is performed for a reaction, and filtering and drying are performed for standby use; (2) obtained solid is dissolved and dispersed into N,N-dimethylformamide to form a suspension, and the suspension is placed in a standing mode for standby use; (3) the polyvinyl alcohol is added into the suspension, the suspension is kept at the temperature ranging from 40 DEG C to 60 DEG C for 6-8 h, glass is coated with a film through a tape casting method, and vacuum drying at the constant temperature is performed to obtain the polyvinyl alcohol-acorn starch-gulcomannan composite material. The obtained polyving akohol-acorn starch-gulcomannan composite material has higher tensile strength and bending strength and is lower in cost, the preparation technology is simple, and the polyvinyl alcohol-acorn starch-gulcomannan composite material is suitable for large scale production.