The invention discloses a carrageenan/methyl cellulose blended membrane, and a preparation method thereof. The preparation method comprises following steps: S1, carrageenan is extracted from Eucheumamuricatum; S2, carrageenan obtained in S1, and methyl cellulose and a polyhydric alcohol are dissolved in double-distilled water, and stirring is carried out for 1 to 3h at 70 to 90 DEG C so as to obtain a mixed solution of carrageenan, methyl cellulose, and the polyhydric alcohol; S3, the mixed solution is subjected to membrane forming and curing; and S4, an obtained membrane is subjected to rinsing with a polar small molecular solvent, and then is subjected to natural drying. The carrageenan/methyl cellulose blended membrane possesses renewability, biodegradability, and biological compatibility, is relatively high in tensile strength, and possesses the highest pyrolysis rate temperature.