A method and a system for determining a discharging process of a battery are provided. The method includes the following steps. Measuring charging/discharging information of the battery. Calculating a charging/discharging characteristic of the battery according to the charging/discharging information. Aligning the charging/discharging characteristic of the battery according to a comparison characteristic point of a comparison characteristic to obtain an aligned charging/discharging characteristic. Determining whether the battery is normal according to the aligned charging/discharging characteristic or a coulombic efficiency of the battery. Calculating a safety probability of the battery according to the aligned charging/discharging characteristic and resistance of an internal short circuit of the battery when the battery is determined as abnormal. Determining a discharging process of the battery according to the safety probability of the battery.