The invention discloses a fireproof expansion sealing strip which has the effects of shock absorption, fire protection, water resistance, sound insulation, thermal insulation, dust prevention and fixing. A sheath of the sealing strip adopts modified PVC; modified expanded graphite is formed inside the sealing strip; expanded graphite inside the fireproof sealing strip on the market can become loose and drop off after being burnt in a big fire, sealing effect is easy to lose, and black toxic smoke can be produced, so that the harm to human body in a fire scene can be improved. The fireproof sealing strip can be expanded but not become loose and drop off after being burnt in a big fire, can maintain integrity, reduce the extension of the fire, cannot generate black smoke, is good in expansibility, completeness and sealing property in case of a fire, and is good in ageing resistance at ordinary times.