The utility model discloses an underground pressure test well opening valve tool suitable for annulus pressurization, which structurally comprises an outer cylinder part and an inner cylinder part; an outer cylinder assembly is formed through an upper joint, a rupture plate outer cylinder, a ball valve outer cylinder and a lower joint; an inner cylinder assembly is provided with a sealed mandrel, a connecting claw, a connecting short joint, an operating arm and a lower pedestal ring from the top down; the connecting short joint and the operating arm are connected in an embedded manner through a flange and a groove; an upper pedestal ring is arranged at an inner opening of the operating arm; a ball valve is arranged between the upper and the lower pedestal rings; a transmission pin is arranged between the operating arm and the ball valve; a belleville spring leaf is arranged between the ball valve and the upper pedestal ring; a shear pin is arranged between the upper joint and the sealed mandrel; and the rupture plate outer cylinder is provided with a rupture plate mounting hole. The ball valve of the underground pressure test well opening valve tool is assembled and descended in a close position, the ball valve is opened through the annular pressure after a test string is completely descended and sealed in a seated manner, and the underground well opening is finished, so that the follow-up testing can be carried out.