Abstract： The etiology and pathogenesis of chronic urticaria are complex， involving not only wind pathogen invading the fleshy exterior and (fire) pathogenic heat accumulating in qi and blood， but also visceral dysfunction. The locations of the disease include the exterior，the interior，the half-exterior halfinterior， and the dual disease of the exterior and interior. Director ZHENG Yihong follows the methods of syndrome differentiation and treatment based on six- meridian syndrome differentiation and formulasyndrome matching and emphasizes the importance of formula- syndrome differentiation over the sixmeridian identification. His flexible use of classic formulas based on formula-syndrome differentiation often achieves good results in the treatment of chronic urticaria. Five medical cases are attached here to illustrate Director ZHENG's experience in formula- syndrome differentiation and the treatment of chronic urticaria with classic formulas.