Three-dimensional flame temperature distribution reconstruction in furnace according to the flame radiative energy images captured by CCD cameras was studied. Temperature reconstruction matrix equation is an ill-posed linear system of equations and the reconstruction problem is an ill-posed problem. Truncated singular value decomposition method (TSVD) was introduced to deal with the ill-posed matrix equation and L-curve method was adopted to choose regularization parameter. Singular value decomposition (SVD) and discrete Picard condition were used to analyze the ill-posed characteristics of the reconstruction problem carefully. The results show that reasonable solutions can be obtained by TSVD and the reconstructed temperature distribution can reproduce the feature of the assumed temperature distribution.