Background: Epidemic keratoconjunctivitis (EKC) is one of the most common eye infections worldwide. The analysis of clinical manifestations in different age groups help better know the disease. This study aims to provide more detailed analysis of 272 cases of EKC in 8 years, describe the differences of the clinical features among different age groups, and establish new clinical grading criteria. Methods: 272 individuals were reviewed (2011-2019) in Beijing China. All the patients were classified into 3 grades according to the new grading criteria. The typical clinical signs of EKC and the photographs of the multiple subepithelial corneal infiltrates (MSI) were collected and analyzed. The number of 3 grades among and within different age groups were compared. The incidence of the typical signs among and within different age groups were compared. The proportion of each region of the cornea involved by MSI were compared. Results: No significant differences were detected among the 4 groups in terms of the number of mild, moderate and severe cases, no matter in all-patients analysis (P = 0.271) nor in acute-phase-patients analysis (P = 0.203). The proportion of the severe cases was the highest among all patients (P = 0.000). Among the incidence of the typical signs, corneal involvement was the most common accounting for 69.8% (P<0.05). The probability of central region involvement was significantly higher than that of pericentral region involvement (P = 0.015) and peripheral region involvement (P = 0.000). Conclusions: Appropriate attention should be paid on EKC, because of the considerable proportion of severe cases, the high incidence of corneal lesion, and the high incidence of central region involvement of MSI.