Three buffaloes were also killed and another injured in the mishap which occurred at Soorappanayakam Chavady, police said.
Vasantha was grazing the buffaloes when some of them strayed onto a nearby railway track.
Seeing the Mayiladuthurai-Villupuram Passenger train approaching the spot, the woman tried to pull her buffaloes away from the track, police said.
But the buffaloes dragged her in the opposite direction and the woman and three of the cattle died on the spot after being hit the train.