Background In December 2019, an outbreak of coronavirus disease 2019 (COVID-19), due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), occurred in Wuhan, China. Patients with COVID-19 were also identified in Chongqing. This study aimed to investigate the clinical and demographic characteristics of cluster cases and sporadic cases of COVID-19 in 141 patients in the main district of Chongqing during one month, between January and February 2020. Material/Methods A retrospective study included 141 patients with a diagnosis of COVID-19. The diagnosis was confirmed using real-time reverse transcription-polymerase chain reaction (RT-PCR) for SARS-CoV-2. The patients were divided into cluster cases (n=90) and sporadic cases (n=51). Demographic and clinical characteristics were compared between the two study groups and included the presence of comorbidities, the presenting symptoms, chest computed tomography (CT) imaging findings, and laboratory findings. Results The mean age of the 141 patients diagnosed with COVID-19 was 47.3 years, and the most common presenting symptom was a persistent cough (48.9%). The 90 cluster cases (63.8%) were older than the sporadic cases, and cross-infection from family gathering occurred in 82.2%, and cough was more common than fever, and there was an increased prevalence of asymptomatic, mild, and moderate cases. Cluster cases showed fewer typical manifestations of COVID-19 on chest CT. However, the laboratory findings between the cluster and sporadic cases showed no significant differences. Conclusions There were demographic and clinical differences between cluster cases and sporadic cases of COVID-19 in the main district of Chongqing during the month between January to February 2020.