Vertical loading test device for maintaining constant pressure and method thereof

The invention discloses a vertical loading test device capable of maintaining constant pressure and a method thereof. The vertical loading test device comprises a vertical loading device and an oil pressure stabilizing device; the vertical loading device comprises a loading jack. The oil pressure stabilizing device comprises a counter-force support, an actuator system, a jack for stabilizing oil pressure and a pressure stabilizing oil way. The fixed end of the actuator system is installed on the counter-force support, and the force application end of the actuator system makes contact with the top face of the telescopic end of the oil pressure stabilizing jack. A base of the oil pressure stabilizing jack is fixed on the counter-force bracket; oil cylinders of the loading jack and the oil pressure stabilizing jack are communicated with the oil pump through an oil supply path; the pressure stabilizing oil way is connected between the oil cylinder of the oil pressure stabilizing jack and the oil cylinder of the l