The invention discloses an organic grass carp forage and a preparation method. The forage is characterized by comprising the following components by weight: 7%-10% of natural fish meal, 15%-20% of organic soybean cake powder, 10%-15% of organic wheat bran, 14%-18% of organic rice bran, 5%-8% of Typha angustifolia powder, 10%-12% of Leersia hexandra grass powder, 6%-10% of zizania grass powder, 3%-8% of yeast powder, 6%-10% of organic vegetable powder, 3%-5% of organic flour, 1%-3% of spirulina powder, 1% of Chinese herbal medicinal powder, 0.1% of EM bacteria, and 0.1% of brown sugar. The formula of the forage involves a plurality of organic raw materials, and provides a forage foundation for organic grass carp production. The organic grass carp forage prepared according to the formula has the advantages of comprehensive nutrition, good palatability, easy digestion and quick absorption. The forage can promote grass carps to grow robustly when it is applied to feed grass carps, which can have strong disease resistance and a high feed survival rate, so that the forage has very good effects on fingerling and adult fish feeding. The organic grass carp forage involved in the invention has the characteristics of wide raw material sources, easy and practical operation, reasonable proportioning, and low cost.