The invention relates to an automatic inducing culture medium for expressing recombinant protein of escherichia coli. Each liter of the culture medium comprises components in parts by weight as follows: 5-10g of tryptone, 3-5g of a yeast extract, 0.1-8 g of sodium succinate hexahydrate, 0.1-1g of sodium citrate dehydrate, 5-15g of glycerinum, 0.1-1g of glucose, 1-4g of lactose, 2-5g of disodium hydrogen phosphate, 2-5g of monopotassium phosphate, 1-4g of ammonium chloride, 0.2-0.9g of sodium sulfate, 0.1-1g of magnesium sulfate heptahydrate, 0.1-0.4g of ferric chloride hexahydrate, 1-3mg of calcium chloride, 0.01-3mg of tetrahydrate manganese chloride, 0.01-5mg of zinc sulfate heptahydrate, 0.01-1mg of cobalt chloride hexahydrate, 0.01-0.5mg of copper chloride dehydrate, 0.01-0.5mg of nickel sulfate hexahydrate, 0.01-1mg of sodium molybdate pentahydrate, 0.04-0.1mg of sodium selenate pentahydrate, 0.001-0.01mg of boric acid, 1-100g of n-hexane and 0.1-10g of calcium peroxide. The automatic inducing culture medium is used for expressing foreign protein, the expression amount of the foreign recombinant protein of the automatic inducing culture medium is increased when compared with that of foreign recombinant protein of an LB (Luria-Bertani) ordinary culture medium, the production cost is saved, environmental pollution is reduced, and the yield can be increased by more than ten times.