Objective To study the dynamic trajectories of quantitative immunoglobulin G (IgG) titers of hospitalized coronavirus disease 2019 (COVID-19) patients and reveal the immune process of the organism after infection.Methods The clinical data and quantitative IgG titers at different time points of hospitalized COVID-19 patients in Wuhan Huoshenshan Hospital and Guanggu Branch of Maternity and Child Healthcare Hospital of Hubei Province from Feb. 5 to Apr. 15, 2020 were retrospectively analyzed. Group-based trajectory modeling was used to identify the subgroups from time-series data of patients’ antibody titers, and then the clinical characteristics and outcomes were compared among these trajectory groups.Results Totally, 734 patients who met the criteria were included. Three IgG trajectory groups were identified from the antibody data: group 1 (consistently low group, 60 cases［ 8.17%］ ), group 2 (moderate group, 38 cases ［5.18%］) and group 3 (high group, 636 cases［86.65%］). The hospitalization days and the virus clearance time of patients in the 3 groups were significantly different (both P＜0.001), those in group 1 were the shortest, while the all-cause mortality and disease deterioration rate had no significant difference in the 3 groups (both P＞0.05).Conclusion Patients with different IgG antibody developmental trajectories may have heterogeneous prognosis and immune process. Patients with consistently higher longitudinal antibody titers may require more medical attention.