Abstract: The optimum technique and conditions of extracting Leaf Protein Concentrate(LPC) from the fresh leaves of Cajanus cauan were studied in this paper, and three methods of precipitating leaf protein with acid, alkali and heat, and the orthogonal design were utilized in this technique.The results showed that the most optimum extracting conditions included the normal temperature, the ratio of 1:3 for fresh leaf to water, the pH of 10, the flocculating temperature of 80℃and 1 minute for the beatig times.By using this technique, about 5.11g of LPC containing about 33.37% of real protein were extracted from 100g fresh leaves and about 64.06% of total nitrogen in fresh leaf of Cajanus cauan was retrieved.