The invention discloses a quick-radiating fixture with stable structure for casting of special steel. The quick-radiating fixture includes a body, lifting bars, press plates, a fixing platform and vent caps; slide balls are mounted in the body; a slide plate is arranged above the slide balls; the body is movably connected with the slide balls; the slide balls are movably connected with the slide plate; a clamp bar is mounted at the top end of the slide plate; fixing springs are disposed above and below the clamp bar; the slide plate is movably connected with the clamp bar; the clamp bar is fixedly connected with the fixing springs; the lifting bar is mounted above the slide plate; an adjusting handle is arranged on the outer side of the lifting bar; the lifting bar is in screw connection with the slide plate. With a cooling fan, the quick-radiating fixture helps effectively cool a steel material and lower the temperature of the steel material, thereby preventing chances for the steel material to harm workers and improving the capacity of the fixture herein to protect operators.