Method for preparing high-purity losartan

The invention relates to a method for preparing high-purity losartan. The method comprises steps as follows: (1), a losartan crude product is added to an organic solvent or a mixed solvent of an organic solvent and water, and the mixture is heated to reach 20-80 DEG C and stirred; (2), the system is cooled directly or cooled after water is added or cooled to 0-5 DEG C after a part of solvent is evaporated, a material is precipitated, filtered and dried, and losartan is obtained, wherein the organic solvent used in the step (1) is any one of tetrahydrofuran, butanone, acetone and methyl alcohol or is a mixed solvent of any one of the four solvents and water. The losartan obtained with the method has high purity, any individual impurity can be reduced to 0.2% or even under 0.1%, the purity of the losartan can reach 99.5%, the cost of the method is lower, the refining yield is high, and the method is very simple in operation, environment-friendly and suitable for industrial production.