Abstract: Objective To analyze the multi slice spiral CT(MSCT) features of Pneumocystis carinii pneumonia(PCP) in patients with acquired immunodeficiency syndrome(AIDS), and to improve the cognition on the disease. Methods A retrospective analysis was conducted on the lung MSCT findings of PCP in 24 patients with AIDS diagnosed clinically by Anqing Hospital Affiliated to Anhui Medical University from December 2016 to August 2019. The ground glass opacity, pulmonary balloon, interstitial changes and mediastinal or lung hilar enlarged lymph nodes, pneumothorax, and pleural effusion were observed and counted. The features of the lesions such as the configuration, density and range of its distribution were summarizing. Results Among the 24 cases, 18 cases(75.0%) showed diffusing symmetrical lesions in both lungs, mainly in bilateral lung hilar, middle and lower lung fields. Among them, 7 cases(29.2%) had lesions of exudate and fused into patchy consolidation shadow, 10 cases(41.7%) had interstitial changes, presenting as thickens of interlobular septum, subpleural lines or reticulation, paving stone sign and fibrosis of interstitium, 6 cases(25.0%) had pulmonary balloon, 4 cases(16.7%) had "lunar arch sign". Extrapulmonary manifestations included 1(4.2%) pneumothorax, 1(4.2%) pleural effusion, 2(8.4%) pericardial effusion, and 2(8.4%) or lung hilar enlarged lymph nodes. Conclusion The MSCT manifestations of PCP in patients with AIDS have certain characteristics. When AIDS patients have fever, dry cough, dyspnea and other symptoms, combined with typical MSCT imaging manifestations, the diagnosis of AIDS combined with PCP can be considered.