The invention discloses an environment-friendly mixed feed for pigs and a preparation method thereof. The environment-friendly mixed feed for pigs is prepared from the following ingredients in part by weight: the environment-friendly mixed feed is prepared from corn, bean pulp, wheat bran, DDGS (distillers dried grains with soluble), acyl hydroxylation emulsified oil powder, calcium hydrogen phosphate, mountain flour, enzyme preparation, calcium propionate, citric acid, lysine, methionine, threonine and pre-mixture; and functional additives in the premixture comprise histidine, arginine, leucine, valine, corynebacterium glutamicum, L-asparaginate-L-phenylalanine methyl ester, spiral seaweed, glucanase, bacillus subtilis and sodium butyrate. According to the feed, engineering bacteria is utilized to generate glutamic acid through fermentation in an intestinal tract of the pig, the additional amino acids in the feed are balanced, all amino acids are induced to be combined in the small intestine in an ideal amino acid mode to be absorbed, the protein level of the feed and the carbon-nitrogen emission are reduced, a part of amino acids are promoted to be deposited in pork, the pork flavor is improved and the pork quality is improved.