The invention discloses a biodegradable material and a preparation method thereof. The biodegradable material comprises, by weight, 20-50% of material A, 40-60% of material B and 20-40% of PBAT thermoplastic biodegradable plastic. The material A comprises, by weight, 40-60% of PBAT thermoplastic biodegradable plastic, 30-50% of PLA and 8-15% of inorganic filler. The material B comprises, by weight, 40-60% of PBAT thermoplastic biodegradable plastic and 40-60% of starch masterbatch, wherein the starch masterbatch comprises, by weight, 60-70% of starch, 1-3% of coupling agent, 1-3% of paraffin,25-30% of glycerin, 0.1-0.3% of citric acid and 2-5% of epoxidized soybean oil.