A method for calculating the process capacity at a specific temperature of a lithium secondary battery includes a correction to a process capacity (Q3) at a specific temperature (T2) is performed using a value (Q1−Q2) obtained by subtracting the charge capacity (Q2) at the time of the shipping charge from the discharge capacity (Q1) measured at a discharge temperature (T1). A system for calculating a process capacity of a lithium secondary battery is provided.