Draft appendix APU of FAR and CCAR and part J of CS25 all has the requirement for the operation of APU in falling and blowing snow condition. CAAC has not issue the guidance for the compliance method, while FAA and EASA has provided some detail requirements for the certification test, but there are some differences between them. This paper compares the differences between CCAR, FAR and CS25 part J about the falling and blowing snow airworthiness requirements for APU inlet system, and studies the detailed certification test requirements of FAA and EASA. Comparison has been made in snow intensity, environmental temperature, blowing snow, duration time and operation condition. The results show that FAA and EASA are almost same in snowfall intensity, blowing snow condition and test condition, but there are some differences in environmental temperature and test duration. Generally, EASA’s requirements for snowfall test conditions are more detailed. Based on this study, the method of compliance was discussed. This paper provides the guidance for compliance certification test of falling and blowing for APU inlet system.