Abstract: Principles and shortcomings of balance jack control of hydraulic support by use of compensation valve, high pressure internal overflow valve, floating two-way lock and automatic balance valve respectively were analyzed, and an optimal design scheme of the balance jack control loop of hydraulic support was proposed according to pressure characteristics of the balance jack cavity. Automatic fluid replacement and unloading of the balance jack cavity are realized by reasonably disposing components such as hydraulic pressure controlled reversing valve and low pressure unloading valve, so as to solve problem of safety valve frequently opening under non-emergency situation. The simulation and test results verify effectiveness of the optimal design scheme.