Bioluminescence tomography (BLT) is a promising imaging technique which may dynamically and real-timely detect the molecular and cellular activity at the whole-body level in small animal studies. In view of the ill-posedness of the BLT, it is hard to fully reconstruct source density. In addition, the uniqueness theorem on BLT indicates that it is important to employ a priori information for accurate source reconstruction. Hence, we adopt diffuse optical tomography (DOT) technique to provide optical parameters of main tissues as a priori information. Besides, we restrict the range of real source to a permissible region to raise the numerical stability and reduce the ill-posedness of BLT. Next, we forward Spatial Weighed Element based Finite Element Method and compare it's solutions with analytic formula and MOSE. Numerical simulation of homogeneous and heterogeneous phantom demonstrates the source location and density with prior information is better than that not using a priori information.