Objective To establish an accurate and reliable method to determinate residualchloroform amount in freeze-dried live attenuated hepatitis A vaccine. Methods The content ofchloroform was measured by headspace gas chromatography and calculated by external standard method. The specificity, linearity and range, accuracy, precision, detection limit, quantitative limit and durabilityof the analytical method were verified. Results The relative standard deviation RSD) value ofchloroform peak was less than 5% and the degree of separation from other peaks was greater than 1.5. The peak of chloroform in the positive solution was observed during the corresponding retention time,and there was no chloroform peak observed in the reference solution. The concentration of chloroform inthe range of 10-1 000 ng/ml was linearly related to the peak area. The solution recovery rates of thetested samples were between 91. 3% and 99. 0% with the concentrations of 600 ng/ml, and the RSDs were all less than 4%. The quantitative limit concentration was 0. 022 ng/ml. Conclusion The established method has good specificity, linearity and range, accuracy, precision and durability, andaccord with requirements of quantitative measurement.