Community-acquired pneumonia (CAP) is one of the most common infectious diseases and a major cause of morbidity and mortality worldwide, and most of patients visit the emergency department(ED) first. For the EDCAP patients with the characteristics of the acute serious and complicated, ED physician should carry on the accurate diagnosis, severity assessment and early treatment. This paperintroduced characteristic and severity assessment of CAP in ED, treatment therapy and sequential therapy of antibiotics to optimize of antibacterial therapy for CAP.