| To construct the finite element model for the heat transfer of the large-scale complex spacecraft with metal truss structure during reentry aerothermodynamics environment, is the key to accurately predict the temperature distribution of the end-of-life spacecraft during the process of falling reentry and disintegration. In this paper, the four-node tetrahedron element is used to discretize the space, and the heat transfer equation is discretized into the algebraic equation sets. The stiff matrix with symmetrically positive, highly sparse and non-zero element distribution is obtained by the overall synthesis of the finite element method. The one-dimensional variable bandwidth storage technique is developed to effectively resolve the data storage of large sparse matrix. To effectively depress the temperature oscillations appeared in time and space in the solving process, the centralized heat capacity matrix coefficient method is developed. The same row or column elements of the heat capacity matrix are summed and substituted by the diagonal elements, so that only the diagonal elements of the new heat capacity matrix exist, and the remaining elements are zero. The two-point backward difference scheme, Crank-Nicolson scheme and Galerkin scheme are constructed to solve the three-dimensional transient temperature field. By computational analysis of transient heat transfer of the rectangular cylinder body, the converged temperature solutions of the above-said three schemes are in good agreement, and the results are consistent with that of the existing finite-element ANSYS software, which confirms the precision and reliability of the present 3D finite-element model for transient heat transfer. The heat transfer computation is carried on the shell structure of the low-orbit spacecraft made of aluminium alloy, and the transient temperature distribution of the Tiangong’s two-capsule structure is simulated and analyzed from the flight altitude of 107.5km~90km, which provides the theoretical support and computable model for the forecast of disintegration of the end-of-life spacecraft during falling reentry.