The invention provides a low-protein mule duck feed for balancing amino acid. The feed comprises a component A and a component B, wherein the component A is prepared in such a way that compound probiotic strains are activated by brown sugar water and then inoculated in a mixture of pulverized corn, rice bran, wheat bran, peanut meal, rapeseed meal, soybean meal, calcium hydrophosphate and table salt, and the mixture is added and mixed with water and then packed in a vacuum bag to ferment 7 days at constant temperature; the component B comprises corn, broken rice, wheat, soybean meal, cottonseed meal, coleseed meal, rice bran, wheat bran, stone powder, calcium hydrophosphate, table salt, a microelement premixture, a vitamin premixture, L-lysine hydrochloride, DL-methionine and phytase wheat enzyme; at the age of 1-3 weeks, the component A and the component B are mixed at the weight part ratio of (15-40):(60-85); at the age of 4-8 weeks, the component A and the component B are mixed at the weight part ratio of (5-15):(85-95). The feed provided by the invention activates the digestion potential of mule ducks, improves feed transformation efficiency, exploits the growth potential of the mule ducks and saves protein resource.