Discussed is a battery diagnosing system that may include a battery management system (BMS) configured to obtain battery information including at least one of a temperature, a current and a voltage of a battery, and generate a first diagnosis result corresponding to a current state of the battery based on the battery information; and a server configured to receive the battery information and the first diagnosis result from the BMS, generate a second diagnosis result corresponding to the current state of the battery and a third diagnosis result corresponding to a future state of the battery from the battery information based on a state estimation model, which is pre-trained, and determine the current state of the battery based on a plurality of diagnosis results of the first diagnosis result, the second diagnosis result and the third diagnosis result.