Abstract:
The long-term fever of unknown origin(FUO) is a common pediatric disease，whose etiology is complex and clinical diagnosis is difficult. This paper expounds Professor Yan Yongbin′s theory in treating FUO based on damp-warm syndrome，who sticks to the TCM theory and refers to the western medicine, stating clear the etiology and pathogenesis and properly using Ganlu Xiaodu micropills. This medicine results in significant clinical effect through clearing heat and toxin and eliminating dampness. It not only expands the scope of application but also innovates and develops the TCM theory on FUO.

Key words: Long-term fever of unknown origin, Ganlu Xiaodu micropills, Damp-warm, Etiology and pathology, Children