A method for the determination of casein phosphopeptide (CPP) in infant formula milk powder by high performance liquid chromatography (HPLC) was developed. Casein phosphopeptide was extracted with water by ultrasonic treatment. The analysis was performed on a ODS column using 0.1% acetic acid and acetonitrile as the mobile phase under gradient elution. The limit of detection of the method was 6.25 mg/kg, the calibration curve was linear between 5.0 and 100.0 μg/mL. Recoveries were between 71.4% and 94.2%. This method was simple and the results complied with the qualitative and quantitative requirements. It therefore can be used to detect casein phosphopeptide in infant milk powder.