The conjugated estrogenic mixture extracted from Pregnant Mares’ Urine(PMU) is chiefly used for hormone replacement therapy (HRT) in the medical service. There are two hundred compounds in Pregnant Mares’ Urine. The extensive research programs directed toward the total synthesis of the female sex hormone were well under way in 1935. US Pharmacopeia(USP)has been added to estrone, equilin and 17α-dihydroequilin as the most important compounds of PMU. But the 17α-dihydroequilin in the PMU originated from Xinjiang is failed to meet the USP requirements, so the synthesis of it is imperative. Synthesis of derivatives of estrone used to synthesis of 17α-dihydroequilin have been studied in this dissertation. The key work is to introduce an unsaturated bond into the B ring of steroid. However, it should be noted that the formation of unsaturated B ring of steroid from △7-ketosteroids has been not observed previously. The thesis is aimed to synthesize the 17α-dihydroequilin by two strategies and some important synthetic intermediates. Additional a synthetic approach to introduce unsaturated bonds into the B ring of steroid were accomplished. Occasionally a methodology of conversation the A ring to the non- aromatic ring in mild condition has been found. All the work above have been a good preparation of the later synthetic work, which is very helpful to the export of the domestic PMU.