Mucous phlegm in the deep nasal cavity is usually seen in acute rhinopharyngitis or acute sinusitis attacks. Acute nasopharyngitis is commonly seen in acute rhinitis or sinusitis, acute tonsillitis, acute pharyngitis, and when the inflammation is severe, it will spread to the nasopharynx and cause the mucous membrane of the nasopharynx to become congested and edematous, and the patient will experience dryness and pain in the nasopharynx with mucus-like discharge. The first step in the examination is to examine the electronic nasopharyngoscope, which can reveal bilateral mucous membrane edema and congestion in the nasopharynx, with mucus secretions or yellow secretions covering the surface. In terms of treatment, acute nasopharyngitis requires symptomatic anti-inflammatory treatment, oral anti-inflammatory drugs, and nebulized inhalation with budesonide nebulization twice a day, which can gradually cure in about a week. Acute sinusitis because the opening of the sinuses is just in the lower nasal tract, so when there is inflammation in the sinuses, the secretions in the sinuses will flow from the nasopharynx into the mouth, which leads to mucous phlegm in the deep nasal cavity, and the diagnosis can be confirmed by examining sinus CT in this case. Sinusitis in the acute stage requires symptomatic anti-inflammatory treatment and oral anti-inflammatory drugs. In case of chronic recurrent sinusitis, surgical treatment is required to cure it.