Automatic Tool Changer(ATC) is composed of tool magazine and tool changing arms. Automatic too changer is installed separately from machine tool with the purpose of preventing adverse influences of vibration during running of automatic tool changer and other reasons on precision. Tool selection adopts the method of fixed address in the shortest path. All tools return to original position, therefore, the problem of collision between large-size tools is only considered in initial installation. Two-way tool magazine adopts the shortest path.