The invention discloses an artificial algal reef and a manufacturing method thereof, and relates to the artificial algal reef and a preparation method thereof. The artificial algal reef comprises an algal reef main body made from reinforcements and concrete; vegetable gum grains are arranged on the algal reef main body, and have the grain size of 1 to 60 mm; and the weight of the vegetable gum grains is 0.01% to 0.6% of the total weight of the artificial algal reef. The preparation method of the artificial algal reef comprises the following steps: 2 to 6 parts of cement, 3 to 10 parts of sand, 8 to 12 parts of stone and 0.001 to 0.008 part of vegetable gun grains are selected through proportioning in part by weight, wherein the grain sizes of the vegetable gum grains are 1 to 10 mm; the algal reef is prepared from cement, sand, stones and a reinforcement cage; and the vegetable gum grains are added before hardening. When the artificial algal reef is used, vegetable gum is dissolved in the water, a microcellular structure is formed on the surface of a reef, the roughness of the surface of the reef is increased, the adhesion possibility of algae spores is improved, a sessile substrate suitable for the adhesion and the growth of the algae spores is provided, and habitats for foraging, breeding, growing and the like are provided for aquatic organisms such as fishes.