The invention relates to a synthesis method for methane and provides a method for synthesizing butoxy methoxy methane used in an ethylene glycol monobutyl ether approach. In the invention, a novel synthetic route for ethylene glycol monobutyl ether is opened up, and a preparation method for butoxy methoxy methane is disclosed. According to the synthetic route, methylal and butanol are used for high-selectivity synthesis of butoxy methoxy methane; then butoxy methoxy methane is subjected to directional carbonylation to produce butoxy methyl acetate; and hydrogenation is carried out on butoxy methyl acetate so as to produce ethylene glycol monobutyl ether and methanol. According to the preparation method, dimethoxymethane and n-butanol in a certain ratio are used as raw materials, a variety of liquid acids and loaded liquid acids are used as catalysts, and butoxy methoxy methane is highly selectively prepared at certain temperature and pressure. The method has the advantages that the raw materials are cheap and easily available; operation in the whole flow is simple; only one product is produced, and high selectivity of the product is realized; and the method has good application prospects and is suitable for industrial production.