Disclosed is a new antibody which can be used to relieve addiction caused by nerve active substances, including opium, cocaine, benzedrine, ketamine, etc. Cocain and amphetamine-regulated transcript peptide antibody gene is selected through phage display technology; then single-chain antibody sequence of the cocain and amphetamine-regulated transcript peptide(CART) and the procaryon expression vector are connected and are induced to express and to be purified to obtain single-chain antibody in response to CART, which is named as CARTscFv(AH1,AH4B,AH6,AH19,AH33B,AH36). Injecteion of CARTscFv into the abdominal cavity of a mouse, together with the CART at the peripheral circulation system, leads to the reduction of the CART in the central nervous system of the mouse. Animal model with behavioral sensitization induced by cocain proves that the CART single-chain antibody can restrain the expression of the behavioral sensitization of the mouse induced by cacain, which shows that the CART single-chain antibody is of great potential in curing addiction and particularly relapse caused by nerve active.