Objective: To research the comparability of water vapor transmission of laminated films for pharmaceutical packaging determined by different instruments, methods and experimental conditions to provide reference and advice for the related inspection personnel.Methods: The principle, test parameters, conditions and scope of application for the testing methods for water vapor transmission in the national standard (GB) and international standards (ISO, ASTM) were compared by using three kinds of instruments based on different testing principles.Results: Different temperature and humidity conditions had great influence on the results of the same instrument.Under the same temperature and humidity, the instrument with different principles had little influence on the test results.Conclusion: Testing personnel should regularly use the standard membrane to calibrate the instrument of the sensor method.The temperature and humidity should be strictly controlled during the test.They should take measurement accuracy, personnel operation and economic loss into consideration to select the suitable method.