Objective To analyze the clinical features of adenovirus pneumonia in immunocompetent adults. Methods The literature about adult patients with adenovirus pneumonia were screened in China National Knowledge Infrastructure (CNKI), Wanfang, VIP, Great Medical Medicine, PubMed, Cochrane Library, Springer Link, Wiley, JSTOR and other databases from the establishment of the database to July 15, 2022. State 16 software was used to conduct a meta-analysis of the clinical features. Results Forty-three literatures representing 2381 adults were included. Among adult patients with adenovirus pneumonia, 96.8% of the patients were male, Human adenovirus type 55 (HAdV-55) and Human adenovirus type 7 (HAdv-7) were the most common types, with lower mortality (0.3%, 95%CI: 0.0-1.5). The common clinical symptoms of adult patients with adenovirus pneumonia were fever (99.1%, 95%CI: 97.5-100.0), following by cough, fatigue, phlegm, and sore throat. The common signs included pharyngeal congestion (74.7%, 95%CI: 57.9-88.7), following by increased heart rate, tonsil enlargement, pharyngeal lymphoid follicle hyperplasia, abnormal respiratory sounds, and increased respiratory rate. The most common complications were pharyngitis (66.6%, 95%CI: 47.9-85.3), following by hypoxemia, acute respiratory distress syndrome (ARDS), respiratory failure, shock, abnormal liver function, hypoproteinemia and electrolyte disturbance. The laboratory test results verified that most patients had normal white blood cell count (68.4%, 95%CI: 60.4-75.9), reduced lymphocyte count (65.5%,95%CI: 44.8-86.1), normal platelet count (79.1%, 95%CI: 74.8-83.3), increased C-reactive protein (82.1%, 95%CI: 67.9-93.2), oxygenation index less than 300 (60.5%, 95%CI: 28.4-88.6), increased erythrocyte sedimentation rate (ESR) (44.3%, 95%CI: 33.2-55.3), and the part patients had increased procalcitonin (PCT) (37.3%, 95%CI: 12.8-65.3). Conclusion Adenovirus pneumonia can also affect immunocompetent adults, and it is more common in middle-aged and young men in the military, mainly with HAdV-55 and HAdV-7 infection. The common clinical manifestations are fever, cough, fatigue, sputum, and pharyngeal pain. The common signs include pharyngeal congestion, rapid heart rate, tonsil enlargement, pharyngeal lymphatic follicular hyperplasia, abnormal respiratory sound, and often complicated with pharyngitis. Most patients had normal white blood cell count, decreased lymphocyte count, normal platelets, elevated C-reactive protein, oxygenation index less than 300, with relatively low mortality.