The invention discloses a liquid-phase discharge shock wave drilling device. The device comprises a shell provided with a fluid inlet section and a fluid outlet section, wherein a liquid-electricity pulse generator is arranged in the shell, and comprises a hollow body, a central flowing channel is formed in the middle of the body, a diversion opening is formed in the upper part of the body, a fluid outlet, a first electrode and a second electrode are formed at the lower part of the body, an electrode gap is formed between the two electrodes, the middle point of the electrode gap is located right below the central flowing channel, a rotary parabolic cavity is formed at the fluid outlet, a rotary parabolic cavity cross section parabola is formed in the section of the rotary parabolic cavity,and a parabolic vertex serves as an origin, the central axis of the shell serves as a y axis, the line which is perpendicular to the central axis of the shell serves as an x axis, the parabolic equation is that y equals a*2, wherein a is a constant. According to the device, the rock breaking can be assisted, and the drilling cost is saved.