Method for hydrogenated preparation of ethylene glycol by oxalic ester

The invention relates to a method for the hydrogenated preparation of ethylene glycol by oxalic ester, which mainly solves the problems in the prior art that reactant fluids are distributed unevenly through a catalyst bed of a reactor, catalyst cannot be utilized sufficiently and evenly, the conversion rate of oxalic ester is low and the target product, i.e. ethylene glycol, has low selectivity and inferior catalyst stability. The method in which the oxalic ester is used as raw material and polar solvent is used as solvent comprises the following steps that: (a) the raw material, the solvent and nitrogen firstly enter a first fixed bed reactor to have a catalyzed reaction with a copper catalyst in order to generate a first reaction fluid containing ethylene glycol; and (b) the first reaction fluid and the hydrogen enter at least one second fixed bed reactor to have a catalyzed reaction with the copper catalyst in order to generate a second reaction fluid containing ethylene glycol; a two-stage porous baffle-t