The invention relates to the technical field of straws, and provides a degradable environment-friendly straw and a preparation method thereof, the degradable environment-friendly straw comprises the following components by weight: 2-8 parts of sodium alginate, 0.5-5 parts of pectin, 0.5-2 parts of welan gum, 8-30 parts of modified starch, 5-10 parts of a plasticizer, 0.5-1.5 parts of tea polyphenol, 0.4-1.2 parts of chitosan oligosaccharide, 0.2-1 part of calcium gluconate, 0.5-2 part of tartaric acid and 50-100 parts of deionized water. The straw is safe and sanitary, free of toxic and side effects, environmentally friendly, edible, easy to degrade, suitable for wide application and popularization and capable of replacing a disposable plastic straw; therefore, the problems that in the prior art, a disposable plastic straw is difficult to degrade, and environmental and marine ecological pollution is prone to being caused are solved.