This article is mainly to investigate the factors on the refining process of folic acid. The appropriate refining process (complex refining combined acid followed by alkali treatment) was proposed. The synthetic crude folic acid was treated firstly with sulfuric acid with the concentration of 30%, then re-purified with sodium hydroxide to give folic acid with the purity of 97% and total yield of 51.3%. Higher temperature (80-100°C) is desired for the crystallization of folic acid. The product treated in this process meets the requirements of CP, USP and BP.