Abstract: Within the framework of the SAARC，South Asian nations started their antiterrorism cooperation，setting up organizations，signing relevant agreements. After the 9.11 terrorist attacks，Pakistan joined the coalition against terrorism led by the United States，and intensified its suppression of the domestic terrorists，which，however，made their nationals suffering. The antiterrorism cooperation mechanism at the regional level has made great progress，and has achieved some success. Besides，Pakistan has also launched a bilateral joint antiterrorism cooperation with India. Counterterrorism cooperation in South Asia has made certain progress in restraining the spread of terrorist activities，and in cutting off the financing sources of terrorist organizations. But further and wider cooperation is restricted by the longterm confrontation between India and Pakistan.

Key words: terrorism, anti terrorism cooperation, cooperation mechanism, India, Pakistan