In order to study the dimensional stability of TATB based polymer bonded explosive(PBX) undergoing heating and irradiation environmental impact, the thermal expansion property of the PBX after high temperature accelerated aging test, γ and neutron irradiation test was studied. Results show that the thermal expansion coefficients of the PBX after aging at 55 ℃, 65 ℃ and 75 ℃ for 60 days decreases, and the thermal expansion coefficients decreased more as the age temperature higher. But the thermal expansion properties of the PBX after γ and neutron irradiation under a certain condition are not obviously changed.