The utility model discloses a testing device for a balance mechanism of a hydraulic support. The hydraulic support comprises a top beam, a shield beam, a base, a stand column, a front connecting rod, a rear connecting rod and a balance jack. The method comprises the steps that firstly, the front connecting rod at one side of the hydraulic support is removed, after the hinged joint between the upper end of the rear connecting rod at the side and the shield beam is removed, the rear connecting rod is installed at the original hinged joint position between the upper end of the front connecting rod and the shield beam, and the rear connecting rod and the shield beam are fixed with each other; then, the stand column is lifted to pitch up the top beam, an rod cavity of the balance jack is pulled till a safety valve is unloaded, the rod cavity of the balance jack is pulled out for 30 mm or even more, then the stand column is descended to get the top beam to be lowered, the rod cavity of the balance jack is pulled till the safety valve is unloaded, the rod cavity of the balance jack is pulled back for 30 mm or even more, the process that the stand column is ascended and descended once is a cycle, and the total number of the cycles is 4000 at a minimum. The expansion amount of the balance jack is controlled through time, it is testified through the test that the mean time when the balance jack is extended out for 30 mm is set to be the liquid supply time, the strength of the balance mechanism can be better verified, and the accidents in the well can be reduced.