Liquid metal battery（LMB）is a kind of new energy storage battery with such characteristics as large capacity

large charging and discharging current as well as long service life. The principle of the LMB is introduced firstly in this paper

the charging and discharging characteristic of the battery is obtained by the experiment and

on the basis of such features of the battery as low charging and discharging voltage and long platform

the series compound equilibrium mode is proposed of the battery. The battery group is formed with 4 batteries as the basic unit

the resistive passive equalization circuit is adopted to achieve the single battery equilibrium. The active equalization is designed by the use of inductance transfer circuit so to achieve equalization among the batteries and

on this basis

the equalization strategy of the battery group during the charging and discharging period is given. The designed compound equilibrium mode is used to test the series circuit of the 24 batteries. Test results show that this equalization mode can achieve implement of multiple batteries in series

which lays a good foundation for the development of battery management system（BMS）.