In order to research the thickness distribution laws of Ti₂ AlNb alloy when it is deformed with the superplastic free bulging in high temperature, the Ti₂AlNb sheet with an uniform initial thickness, has been studied by the finite element simulation and experiment in this paper. Laws of the limit bulged samples are experimented in the 910℃, 930℃, 950℃ and 970℃. And the thickness distribution of finally bulged samples are simulated numerically with the constant strain rate. It is found that, the spherical thickness distribution is uneven after bulging; and Ti₂ AlNb sheet is bulged into irregular spherical easily; and the temperature relatively effects the spherical shape and the thickness as well. The temperature can affect the thickness distribution of Ti₂ AlNb alloy sheet formed by superplastic free bulging, based on which the temperature sensitivity index n is considered to correct the E-K model which predicts the thickness of the bulged sheet. The study provides a reference basis for the superplastic deformation of complex thin-walled structures in aerospace of Ti₂AlNb alloy.