Using HPLC method, the content of ethambutol hydrochloride capsule was determined rapidly and simply. The chromatographic conditions were that  selecting HPX-87C column and refractive index detector, the mobile phase was ultra pure water, the column temperature was 70 ℃.The content of ethambutol hydrochloride capsules  was detemined with the external standard method. The results showed that  the specificity of the method was good, ethambutol hydrochloride concentration linear in the range of 0.5~5 mg/mL  was good, the correlation coefficient was 0.999 3, the recovery rate was 99.6%, RSD was 0.42%, and it had good stability, the results between this method and the Pharmacopoeia method had no obvious difference, and had the features of simplicity and speediness, could be suitable for the determination of the content of ethambutol hydrochloride capsule.