Macrophage activation syndrome (MAS) is a rare complication of Kawasaki disease and more attention is needed for it in clinic because of its insidious onset, rapid progression, multiple organ system involvement and high mortality. There is no international unified diagnostic criteria and treatment regimen for Kawasaki disease complicated with macrophage activation syndrome at present, so it is often missed or misdiagnosed. This article reviews the epidemiology, immunological mechanism, diagnosis and treatment of Kawasaki disease complicated with macrophage activation syndrome.