This invention provides a method for preparing ethylene glycol by hydrolysing ethylene glycol monomethyl ether. The method comprises passing a fresh raw material containing ethylene glycol monomethyl ether and water through a reaction zone loaded with a solid acid catalyst to react under the following conditions; separating the reacted mixture via a separation system to obtain a target product of ethylene glycol, by-products containing methanol, dimethyl ether and ethylene glycol-based derivatives, and an unreacted raw material containing ethylene glycol monomethyl ether and water; passing the target product of ethylene glycol into a product collection system; and passing methyl alcohol and dimethyl ether in the by-products into a by-product collection system; and after being mixed with the fresh raw materials containing ethylene glycol monomethyl ether and water, the ethylene glycol-based derivatives in the by-products and the unreacted raw material containing ethylene glycol monomethyl ether and water being recycled into the reaction zone, to realize the preparation of ethylene glycol by hydrolysing ethylene glycol monomethyl ether. This invention provides a new process to realize the preparation of ethylene glycol by hydrolysing ethylene glycol monomethyl ether. And in the method, the catalyst has long life and good stability.