The conjunctiva is a soft, smooth and transparent membrane located on the inner surface of the eyelid and the surface of the eye. Conjunctivitis is a common and prevalent clinical condition. The first step in conjunctivitis is to identify the cause of what is causing the conjunctivitis. The etiology of conjunctivitis can be divided into two categories, infectious and non-infectious, depending on its different nature. (1) Infectious: inflammation of the conjunctiva due to infection by pathogenic microorganisms. (2) Non-infectious: allergic inflammation caused by local or systemic allergic reactions is the most common. External physical and chemical factors such as light and various chemicals can also be causative factors. In the case of infectious conjunctivitis, the following methods are used: (1) Flushing of the conjunctival sac, using saline is sufficient, its role is mainly to cleanse, do not cover the affected eye. (2) Topical medication, antibacterial or antiviral eye drops or eye ointment. Depending on the pathogenic diagnosis, choose the appropriate therapeutic drugs. (3) Systemic therapy For severe conjunctivitis, a combination of systemic medications is required. In case of non-infectious conjunctivitis, such as allergic conjunctivitis, do not abuse antibiotics, but use anti-allergic eye drops, such as sodium cromoglycate eye solution. Therefore, conjunctivitis should be treated according to the specific cause.