Objective: This study aims to investigate the constitution, mucosal inflammation, Chinese medicine syndrome types, and the clinical pathological characteristics of patients with IgA nephropathy (IgAN). Methods: Through a cross-sectional and retrospective study, we investigated 262 patients with IgAN in Guangdong provincial TCM hospital and the Third Hospital of Peking University between January 2011 and January 2014. Chinese medicine syndrome types, clinical and pathological data, constitution questionnaires, and the mucosal inflammation were obtained. Results: The constitution of the Yin-Yang harmony was the most common (40.5%), followed by Qi-deficiency (31.3%). Upper respiratory infection, chronic periodontitis and cystitis were common in patients with IgAN. Qi-deficiency of the spleen and kidney was the common type: 69.1%. Asymptomatic abnormal urinalysis (50.4% of patients) and CKD 1 (48.5%) were the most common clinical presentations. Haas was the most common pathological presentation (47.3%). In patients with Qi-deficiency of the spleen and kidney, the constitution of the Yin-Yang harmony presented with more non-mucosal inflammation, more CKD3-4, higher serum creatinine, urea nitrogen, and serum CH50 lever, and lower GFR, when clinically compared to patients with the constitution of Qi-deficiency. Conclusions: Asymptomatic abnormal urinalysis is the most common clinical type. Frequent upper respiratory infection, chronic periodontitis and recurrent cystitis were common in patients with IgAN. For IgAN patients with Qi-deficiency of spleen and kidney, the constitution of the Yin-Yang harmony had higher serum CH50 levels, lower incidence of mucosal inflammation, increased risk of declined renal function and more severe renal pathological changes.