Objective: To investigate the clinical features, endoscopic appearance and genetic characteristic of a child with activated phosphoinositide 3-kinase δ syndrome (APDS) with onset of recurrent bloody stools. Methods: A 19-month-old girl who was diagnosed with APDS because of PIK3CD mutation was admitted into Ruijin Hospital in December 2018. The clinical manifestations, biochemical tests, immunological function, treatment, and follow-up of the patient were analyzed.And Chinese database and PUBMED database were searched for literature review. Results: The child had chronic diarrhea and suffered intestinal infection for 4 times. Serum immunoglobulin levels were decreased: IgG 1.16 g/L,IgA 0.11 g/L, IgM 2.81 g/L. The T cell subset detection found increased CD8⁺ and decreased CD4⁺: CD3⁺ 61.30%, CD3⁺CD4⁺ 26.30%, CD3⁺CD8⁺ 33.80%, CD56⁺CD16⁺ 27.80%, CD19⁺10.40%. Colonoscopy found lymphonodular hyperplasia. A mutation of c.3061G>A(p.E1021K) in PIK3CD gene was found by whole-exome sequencing. Related literature searched showed that APDS patients had repeated respiratory infections, CM virus and/or EB virus infection, lymphoid tissue hyperplasia as the main manifestations. Conclusions: This is the first report of a case of APDS with onset of recurrent bloody stool in our country. For low aged children who has repeated bloody stools, especially those with lymphonodular hyperplasia found under colonoscopy, should have abnormal immunological findings tested and differentiated from primary immunodeficiency diseases.APDS could be diagnosed by relevant genetic test.