Kasabach–Merritt syndrome (KMS) is a rare complication of hemangioma. KMS mostly occurs in the pediatric population with typical clinical manifestations, including thrombocytopenia, consumptive coagulation, and purpura. However, the pathogenesis of KMS is still unclear and the KMS therapy is controversial. We report here a case of KMS and multiple, giant, hepatic hemangiomas in a 34-year-old female patient who was successfully treated in our hospital. Glucocorticoid along with supportive treatments was administrated immediately to reverse fatal disseminated intravascular coagulation and acute hemolysis. After the acute phase, glucocorticoid was tapered slowly and sirolimus was added to treat the hemangiomas. In conclusion, the risk factors of gestation, interventional treatment, and autoimmune disturbance might contribute to the pathogenesis of KMS. Additionally, treatment with glucocorticoid and sirolimus is effective in KMS and multiple giant hepatic hemangiomas.