The invention provides a small-size quickly separated firer-unlocking bolt. The small-size quickly separated firer-unlocking bolt comprises an unlocking bolt main body (1), a sealing ring (2) and a semiconductor bridge-type pressure cartridge case (3). In the small-size quickly separated firer-unlocking bolt, a semiconductor bridge firing element is adopted as a firer connection and separation mechanism of the firing element; the whole axial length of the small-size quickly separated firer-unlocking bolt is 60 to 65 millimeters, and the radial size is less than or equal to 16 millimeters; the separation time of the small-size quickly separated firer-unlocking bolt is 1.0 to 1.1 microseconds, the separation synchronism is 0.10 to 0.15 microseconds, and the connection bearing capacity is 21 to 25kN. The small-size quickly separated firer-unlocking bolt has the characteristics of small structural size, short separation time, high synchronism, low firing energy and the like; a safe, quick and synchronous separation function of the interstage of a spacecraft can be realized; the small-size quickly separated firer-unlocking bolt can be directly applied to interstage separation systems of the spacecrafts such as high-speed guided missiles, airships, satellites and the like; meanwhile, a beneficial reference is provided for a design of a similar power source firer mechanism.