The invention provides a method for preparing ethylene glycol and 1,2-propylene glycol by using a high-concentration saccharide solution. Reaction raw materials comprise cane sugar, glucose, fructose, fructosan, xylose, soluble lower polyxylose and soluble starch. According to the method, high-concentration saccharide is used as a reaction raw material, and a high-pressure pump feeding mode is used in a reaction process which is performed in a high-pressure reaction kettle; iron, cobalt, nickel, ruthenium, rhodium, palladium, iridium and platinum which serve as transition metal in eighth, ninth and tenth groups are used as hydrogenation active ingredients; the hydrogenation active ingredients form a composite catalyst together with metal tungsten, tungsten carbide, tungsten nitride, tungsten phosphide, tungsten oxide, tungsten sulfide, tungsten chloride, tungsten hydroxide, tungsten bronze, tungstic acid, tungstate, metatungstic acid, metatungstate, paratungstic acid, paratungstate, peroxotungstic acid, peroxotungstate and tungsten-containing heteropolyacid which serve as catalytic active ingredients; and the high-concentration saccharide solution can be efficiently prepared into the ethylene glycol and the propylene glycol at high selectivity and high yield in a one-step catalytic conversion process under the hydrothermal condition that the temperature is 120 to 300 DEG C and the hydrogen pressure is 1 to 13MPa. By the method, the problem of coking of the high-concentration saccharide in the catalytic conversion process can be effectively solved, and high-concentration ethylene glycol and propylene glycol can be prepared by the high-concentration saccharide.