The invention relates to a preparation method for progestin. 4-androstenedione is used as a raw material. The preparation method comprises the following steps: A, etherate is synthetized, wherein the 4-androstenedione and triethyl orthoformate perform an acid catalyzed reaction in organic solvents of dichloromethane, low-carbon alcohol and the like to obtain the etherate 3-ethoxy-androstane-3, 5-diolefin-17-ketone; B, a nitro substance is synthetized, wherein the etherate in the organic solvents and nitroethane perform 17-bit addition under the catalysis of ethylenediamine to obtain the nitro substance 3-ethoxy-20-nitro-pregnane-3, 5, 17 (20)-triene; and C, the progestin is synthetized, wherein the nitro substance is reduced by zinc powder in organic solvents of acetic acids, low-carbon alcohol and the like, acid hydrolysis is performed, so that semi-finished products of the progestin are obtained, the semi-finished products of the progestin are decolored and refined by alcohol and activated carbon to obtain the progestin, the content of HPLC is more than 99.5%, the melting point is 128-131 DEG C, and the total yield of synthetized weight is 83-87%. When the method disclosed by the invention is used for producing the progestin, the yield is high, the degree of purity is good, the quality is stable, the solvent recovering rate is high, and the method is economic and environment-friendly.