To meet the requirement of measuring the lithium bromide solution concentration in `The Research on the heat and mass transfer process of plate falling film absorber with a film-inverting configuration', by analyzing the principle of the concentration measurement method by using the Hydrometer, and based on the principle of the electromagnetic force torque feedback balance, Data acquisition and etc. This paper designed a new kind of lithium bromide solution concentration automatic measurement system, built the corresponding experiment system and tested it. The test results of the experiment system showed that, this new system can measure the lithium bromide solution concentration accurately, conveniently and quickly.