A method for fabricating a carbon nanotube yarn includes providing a plurality of carbon nanotube arrays; pulling out, by using a tool, a first carbon nanotube structure from one of the carbon nanotube arrays; pulling out a subsequent carbon nanotube structure from another one of the carbon nanotube arrays; joining a leading end of the subsequent carbon nanotube structure to a trailing portion of the carbon nanotube structure already formed by contacting the leading end of the subsequent carbon nanotube structure with the trailing portion of the already-formed carbon nanotube structure, with the contact occurring along a common lengthwise direction of the two carbon nanotube structures, thereby forming a lengthened carbon nanotube structure; repeating the pulling and the joining until the lengthened carbon nanotube structure has a desired length; and treating the lengthened carbon nanotube structure with an organic solvent.