Big-data-based battery diagnostic system and control method therefor

Disclosed herein is a big-data-based battery diagnostic system that includes a first vehicle having a first battery module disposed therein, a battery data server having a processor configured to collect first state information related to the first battery module provided from the first vehicle, to learn the collected first state information, and to set a reference voltage for the first vehicle based on the learned first state information, and a second vehicle configured to receive the reference voltage from the battery data server and having a second battery module disposed therein. The second vehicle is configured to measure second state information related to the second battery module, compare the measured second state information with the reference voltage to analyze the same, and apply a result value of the comparison and analysis to a preset diagnostic level range to diagnose a current state of the second vehicle.