The invention provides a chicken feed additive for increasing the DHA content of eggs, characterized in that, the additive is prepared by fish oil, algae powder, flax seed, each of 27.5-60%, 22-24.5% and 45.5-48.5% by weight. The feed additive to feed chicken is prepared by mixing the fish oil, algae powder, flax seed with the weight ratios above well. While using, the prepared additive is added in the normal feeds, and the adding amount thereof is 4-8% of the total weight of the normal feeds, namely, 40-80kg added in the normal feeds per ton, most suitably, 60kg. The feed additive of proper amount added in the normal feeds to feed the chicken is capable of increasing the DHA content in the eggs by 5-6 times, and is high in nutrition, suitable for health of consumers, low cost and easy operation.