The state of health (SOH) of the lithiumion battery is evaluated to provide an important reference for battery safety, charge and discharge control, heat management and other functions. Regional capacity analysis (RCA) based on capacity incremental analysis (ICA) is proposed, and the concept of regional voltage and regional capacity is introduced. The ICA analysis of the lithium iron phosphate (LFP) battery module charged voltage data at different magnifications, extracted the highest peak value of the IC curve and the regional capacity of RCA as health factors, and established mathematics model between health factors and SOH. The results show that the goodness of fit (R2) of the linear relationship between the highest peak and SOH is 0815 4 in the charging stage and 0874 1 in the discharging stage when the chargedischarge rate is 1 C, while the R2 of the linear relationship between the regional capacity and SOH is 0984 2 in the charging stage and 0957 6 in the discharging stage; When the chargedischarge rate is 2 C, the fitting degree of the highest peak as a health factor of SOH in the charging stage is only 0188 4, and the fitting degree of the discharging stage is 0576 7, while the fitting degree of the regional capacity to SOH in the charging stage is 0894 2, and the R2 in the discharging stage is 0988 2. It can be seen that when the chargedischarge rate is 1 C or 2 C, the regional capacity is better as a health factor to evaluate the SOH of the battery. The research results have important reference value for the evaluation of battery SOH at large current rates.