BACKGROUND Wilson disease (WD) is a genetic disorder of hepatic copper excretion, leading to copper accumulation in various tissues. The manifestations are quite variable, and hemolytic anemia is the most common hematological presentation. WD associated with thrombocytopenia is very rare. CASE SUMMARY We report the case of an 11-year-old Chinese girl with WD that was associated with immune thrombocytopenia (ITP). Thrombocytopenia was the initial chief complaint for her to visit a hematologist, and ITP was diagnosed based on the results of a bone marrow biopsy and positive antiplatelet autoantibodies. About two weeks before the thrombocytopenia was found, the patient developed drooling. Tremors developed in her right hand about one week after being diagnosed with ITP, after which she was admitted to our hospital. Further evaluations were performed. Ceruloplasmin was decreased, with an increased level of copper in her 24-h urine excretion. Kayser Fleischer's ring (K-F ring) was positive. The ultrasound showed liver cirrhosis, and brain magnetic resonance imaging showed that the lenticular nucleus, caudate nucleus, and brainstem presented a low signal intensity in T1-weighted images and high signal intensity in T2-weighted images. WD was diagnosed and a genetic analysis was performed. A compound heterozygous mutation in ATP7B was detected; c.2333G>T (p.Arg778Leu) in exon 8 and c.3809A>G (p.Asn1270Ser) in exon 18. The former was inherited from her father and the latter from her mother. However, her parents showed normal liver function and negative K-F rings. Such a compound mutation in a case of WD associated with ITP in children has not been published previously. CONCLUSION WD can associate with thrombocytopenia but the mechanism is still unclear. We recommend that antiplatelet autoantibodies should be tested in WD patients with thrombocytopenia in future to verify the association.