The invention discloses a triaxial one-time coal and gas outburst test device. The device comprises a main pressure chamber and a primary pressure chamber, wherein the main pressure chamber comprises a confining pressure chamber base, a steel cylinder, a confining pressure cavity upper cover, an outburst opening sealing taper sleeve, a sealing aluminium sheet, a sealing screw plug, a lifting screw rod, a driving mechanism, a load sensor, a lower bearing plate, a confining pressure piston, a telescopic steel sleeve and a rubber sleeve, wherein the driving mechanism can drive the lifting screw rod to ascend or descend; the primary pressure chamber comprises a pressure chamber sleeve, spring lock pins, a piercing tool, an energy storage spring base, energy storage springs, a top cover, a sealing aluminium sheet II and a sealing screw plug II; the primary pressure chamber is installed at the top of the main pressure chamber; and the piercing tool aligns to a sealing aluminium sheet I on the main pressure chamber. The test device can adopt raw coal in different sizes to carry out coal and gas outburst test in the triaxial stress state to study the coal and gas outburst occurrence principles more comprehensively and scientifically.