To control the double-telescopic hydraulic support of the coal mine, to control the sequence of stretching of the two-stage cylinder with movable column: it is a mechanically open one-way valve, which, by adjusting the opening pressure, ensures that when the column is stretched, it first exits the first-stage cylinder and then exits the active column; With bracket support, the bottom valve is closed, the two-stage cylinder is subjected to the same working resistance: when the column is lowered, the first stage cylinder is lowered first, lowered to the bottom to open the bottom valve, the second stage cylinder returns the liquid, the living column is grounded.