The conjugate linoleic acid (CLA) was prepared by the alkali isomerization with sunflower oil as raw material. Effects of solvent varieties, reaction time, reaction temperatures, and catalyst dosages on the yield of CLA were analyzed by the single factor experiment and orthogonal experiment with three factors and three levels. The results showed that optimized conditions were as following, 1,2-propylene glycol as solvent, the ratio of sunflower oil and solvent 1∶3, the reaction temperature 170℃, the reaction time 2.5h, and the ratio of alkali and saponification equivalent 2.2. The yield of CLA was 47.80% under the optimized conditions.