The present invention belongs to the technical field of traditional Chinese medicine extraction, and in particular relates to a technique for extracting high purity puerarin and diverse rare medical components from the root of kudzuvine. The method comprises the steps of alcohol ultrasonic leaching, medicine liquid recycling, evaporation concentration for preparing ointment, dissolution and extraction on the soaked ointment and three-step extraction for respectively separating the active components daidzein, allantoin and puerarin. The invention separates, purifies and utilizes the majority of active components in the root of kudzuvine, thus greatly enhancing the comprehensive utilization value of the root of kudzuvine. In particular, in the invention 3'-cyano-group puerarin is separated out of the puerarin with the yield of 3.22% (the content being 98.1%), the component is an unavailable poisonous component in the puerarin, the prior art can not separate the 3'-cyano-group puerarin out, so the medical application of the puerarin is limited.