The invention provides a health food to supplement selenium and vitamin C and a preparation method thereof. The health food is made with, by weight, 0.00192-0.0192part of L-selenium-methylselenocysteine, 5-15 parts of L-ascorbic acid, 78.86-91.26 parts of sorbitol, 1.8-2 parts of citric acid, 0.25-0.27 part of aspartame, 0.34-0.52 part of an edible essence, 0.1-0.5 part of a food color, and 1.04-3.04 parts of magnesium stearate. L-selenium-methylselenocysteine and vitamin C are matched herein; sour-sweet taste of vitamin C well covers the bad smell of selenium; antioxidant action of vitamin Cand selenium are synergistic; sorbitol acts a filling agent and cannot convert into glucose after eating, so that the health food is suitable for most people, including diabetics, to eat; tablets of different flavors suitable for buccal use are made by adding citric acid, aspartame and edible essence to adjust the product taste; the tablets can be taken at any time anywhere with no water, administering is greatly facilitated, and the tablets are suitable for most people.