Abstract: Objective To investigate the relationship between hospital stays or duration of clinical symptoms and total immunoglobulin E levels in children who were diagnosed allergic purpura. To study the changes of total IgE, IgA and complement C3 in children with allergic purpura. Methods The hospitalized children diagnosed with allergic purpura in the First Affiliated Hospital of Bengbu Medical College from January 2013 to December 2018 were selected as research objects, and the serum allergen total IgE, IgA and complement C3 levels in children with allergic purpura were retrospectively analyzed. T-test of two independent samples was used for analysis, and multivariate regression analysis was performed. SPSS 22.0 software was used for data analysis. Results The total IgE levels with the length of hospital stay longer than the total IgE level of normal children, and skin rashes, joints, and the digestive tract symptoms last longer. The hospital stays and symptoms duration of children with reduced complement C3 levels were significantly higher than those with normal complement C3 levels. Children with elevated IgA levels had longer hospital stays than those with normal IgA levels, and the rash, gastrointestinal and joint symptoms lasted longer. The multiple regression analysis showed that the total IgE level had a significant positive correlation with the number of days of hospitalization, rash, abdominal pain and joint pain duration in children with allergic purpura, while the complement C3 level had a significant negative correlation with the number of days of abdominal pain duration, while the IgA level had no significant correlation with the number of days of hospitalization, rash, joint pain and abdominal pain duration. Conclusions The total IgE level of children with allergic purpura can be used as one of the indexes to evaluate and predict the disease outcome. Compared with IgA and C3, the total IgE of children with allergic purpura is more predictive of prognosis. The levels of IgA and IgE are increased in HSP children, while the levels of complement C3 are decreased.