Odysseus used his cunning to beat the Cyclops. In the Trojan war, he knew he couldn't break the walls, but once they got in the walls they could beat the Trojans, so he had them men construct the Trojan horse, hide inside and come out to defeat the Trojans. He used a similar technique here by disguising his name as "No Man." He offered to get the cyclops drunk, told him his name and after he was passed out, Odysseus and his men blinded him. The next morning the Cyclops figures that out and screams out that "no man" has done this to him, confusing the other cyclopses thinking he was still drunk and unable to help out since "no man" did this. This confusion allowed for him and his men to escape.
