As an important part of the passenger oxygen system, the passenger oxygen mask is a common oxygen distributing device to provide emergency oxygen for passengers. With the development of domestic large aircraft project, a continuous airflow passenger oxygen mask has been developed according to the international standards. Due to the extensive equipment of passenger oxygen mask in civil aircraft, it is required to have excellent fire performance. According to CCAR-25-R4 Clause 25.853 and Appendix F Part I, the airworthiness clauses were analyzed. The samples of the silica gel and polyvinyl chloride materials of the main part of the designed mask were prepared by simulated cutting, and the horizontal combustion test of the samples was carried out by using the test method in Appendix F Part I (b) (5) of CCAR-25-R4. The results show that the mask material’s test burning rate of horizontal combustion is 0, which meets the requirement of CCAR-25-R4 Appendix F Part I (a) (1) (iv) that the horizontal combustion test burning rate shall not exceed 64 mm/min, and the flame retardancy of the designed passenger oxygen mask meets airworthiness requirements.