An acid-dye colormetric method was described for the determination of chlorpromazine hydrochloride in the compound preparation. The method was based on the reaction of chlorpromazine hydrochloride with methyl orange, to form a yellow complex, which then was extracted by chloroform and exhibited a maximum absorption at 424 nm. The optimal conditions for determination were selected by orthogonal design test. The linear range of this method was 20-120 micrograms/ml (r = 0.9997). The average recovery of the three sample solutions of different concentrations was 99.72% +/- 0.46% (n = 6). The other ingredients of preparation do not interfere with chlorpromazine determination. This method is more sensitive and accurate and can be used for quality control of this compound preparation.