Orthogonal test was carried on, choosing four factors: liquid-solid ratio, alkali concentration, extraction times and temperature, three levels to optimize the extracting technology of selenium-protein, on the basis of single factor experiments. Through this test, a series of related coefficients about alkaline extraction assisted by freeze-thaw method were optimized. The optimum extraction technological conditions were obtained as follows: NaOH solution 0.1 mol/L, solid-liquid ratio 60︰1 (Ｖ︰m), extracting temperature 70 ℃, extracting time 3 h ,and extracting times twice,. Under these conditions, the extraction ratio of selenium-protein was 60.93%, the purity of which was 52.07%. The resulting crude protein was further purified by ethanol precipitation. The amount of selenium-protein in obtained product was 78.26%, and the loss rate of protein during purification was 7.21%.