A military court in Rostov-on-Don, in southern Russia, found Aleksei Krivoshonok guilty of murdering the three civilians at a roadblock outside the village of Staraya Sunzha, near Grozny, in November 2005.
Prosecutors said he was under the influence of drink and drugs at the time.
Reports say the sentence was the heaviest yet to be handed down to a Russian serviceman found guilty of involvement in what human rights activists say are widespread abuses by the military in Chechnya.
(Compiled from agency reports)
The aftermath of a December 2002 Chechen resistance attack on the main government building in Grozny (epa)