There is no conclusive evidence that wearing multiple layers of masks is better for preventing novel coronavirus infections. Theoretically, although wearing a multi-layer mask can increase the protection effect, it will increase the ventilation resistance and discomfort. When wearing a multi-layer mask for inhalation, the mask has a resistance effect on the air, and when the resistance to inhalation is too large, people will feel dizzy, chest tightness and other discomfort, which is not worth the loss. Therefore, it is not necessary to wear multi-layer masks, for medical protective masks and medical general surgical masks, as long as the correct wear qualified products, only one can prevent the spread of respiratory droplets carrying pathogens, to achieve the protective effect.