This study evaluates the clinical efficacy of Gualou Xiebai Banxia Decoction compounded with Danshen Decoction in the treatment of unstable angina pectoris. All of the patients will be divided into 2 arms randomly. One of the arms will be treated by conventional western medicine, the other one will be treated by Gualou Xiebai Banxia Decoction compounded with Danshen Decoction at the base of conventional western medicine.