Using oxalic acid reagent supported on silica gel 17-cyclic ethylenedioxo-3-methoxyestra-2,5(10)-dien-11b-ol (I) was converted into corresponding 3-one derivative II without migration of 5(10)-alkene bond and hydrolysis of 17-cyclic acetal group. This selective hydrolysis was carried out in mild condition and easily to be controlled. The product can be isolated conveniently with 66.7% yield. This new method is obviously superior to the reported procedures. The product from reaction of I with 70% acetic acid or oxalic acid/methanol is a complicated mixture and difficult to be purified.