Barrios, 25, had her best shot in the second round, enough to secure the runner-up position behind American Stephanie Brown, who had had a 64.74 first shot.
The Cuban athlete had won bronze at the Osaka World Championships last year. She opened this Olympic tournament with another over-63 meter shot, to pass Ukrainian Olena Antonova's 62.59.
Barrios had a shot sequence that included 62.22, 62.12, 60.30 and a foul. This silver medal is the fifth for the Cuban delegation at Beijing and the second this day after the one obtained by cyclist Yoanka Gonzalez in the race by points.