The difference between the crime of producing and selling substandard medical device，stipulated in Article 145 of the Criminal Law，and the crime of producing and selling fake products in terms of the crime target is that there are certain medical apparatus and instruments or medical hygiene materials that are not up to the national or trade standards for safeguarding human health rather than general fake products；the difference in terms of constitutive element is the “sufficiency of serious harm to human health” rather than the amount of production and sales. The nature of producing and selling fake masks during the epidemic situation should be identified from three aspects：the nature of the product，safety standards，and the harm to human health. Producing and selling medical masks belonging to the “Medical Device Classification Catalogue”，or selling masks for epidemic protection and other medical purposes，that are not up to the national or trade standards for safeguarding human health，so that the protection function is insufficient，resulting in delayed diagnosis and treatment and sufficiency of serious harm to human health，should be identified as the crime of producing and selling substandard medical device.