The six Eritreans, accused of racketeering and abetting illegal immigration, face sentences of between eight and 17 years if convicted, Ansa reported.
The overcrowded boat is thought to have capsized after one of the smugglers lit a fire on board to alert the Italian coast guard to their whereabouts, sparking panic among the hundreds of passengers.
Dozens of children also perished in the October 3rd 2013 tragedy.
Two other defendants, believed to have been the leaders of the human trafficking ring, are still at large.
Italy vowed to crack down on human traffickers in the wake of the tragedy, with investigators building their case around survivor testimonies and 30,000 wiretaps, which included conversations among the smugglers about the deaths of their passengers.
In one intercepted conversation, they blamed the migrants for the tragedy,"because they wanted to leave in great numbers".
Meanwhile, a Somali trafficker who raped and attacked migrants he had led through the desert to Libya to make the perilous crossing to Italy was sentenced to 30 years in February. Mouhamud Elmi Muhidin, 34, was identified by several survivors of the October 2013 boat wreck.