Abstract: A method was established to determine the content of calcium chloride in compound sodium chloride injection. By atomic absorption spectrometry, the content of calcium chloride in compound sodium chloride injection was determined under the condition as follows: detection wavelength was 422.7 nm, the flame tape was air/acetylene(13.5∶ 2.0), the lamp current was 10 mA, slit width was 0.5 nm. Good linear relationship of concentration and absorption of Ca²⁺ was within the range of 1 μg/mL-9 μg/mL, the recovery rate range from 98.42% to 100.93%, detectability was 0.008206 μg/mL, the RSD between results obtained from official method and ones obtained from comparative method is 1.21%. This method has good specificity, stability, reproducibility, and is accurate for detecting the content of Ca²⁺, and can be supplementary method to official one. The concentration of calcium chloride in compound sodium chloride injection is between 0.0329296% g/mL and 0.0340398% g/mL, which meets the required quality standards.