Sunil Chhetri, Robin Singh and substitute Alwyn George were on target either side of halftime for the Indian side who were on an exposure tour as part of preparations for the upcoming Asian Games.
One-time runners up Jiangsu are currently placed seventh in the Chinese Super League table having garnered 31 points from 21 matches so far. They fielded their second string side in this match.
India started the match brightly winning three corners in the space of the first 20 minutes. But all three takes from Dempo's Mandar Rao Desai failed to cause enough flutters in opposition ranks.
Soon after, the visiting captain had another glorious chance to double the lead from the penalty spot after Robin was brought down inside the 18-yard box. But the AIFF Player of the Year pulled his take wide.
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In between, Robin could not quite pull the trigger from a one on one situation also failing to keep the ball on target on the rebound. But he made amends on the other side of the half when he leaped highest to powerfully head the ball into the back of the net from Mandar's perfectly weighed right-wing cross.
India next play another side from the Chinese Super League, Shanghai East India on September 6.