Abstract: In this paper，the discharge capacity，stability voltage and the ratio of constant current charge capacity and battery discharge capacity of lithium ion battery were studied. For the lithium manganese lithium-ion batteries，the discharge capacity，mid-value voltage and stability voltage all increased with increasing charge cutoff voltage. As long as charge cutoff voltage was no less than 4.15 V，the battery discharge capacity loss would not exceed 6%. When charge cutoff voltage was 4.15V，the constant current charge capacity accounted for more than 85% of total charge capacity，a little change from 4.20 V. This conclusion provides the experiment basis for sacrificing a small part of capacity and improving the safety performance of battery .