Information fusion in wireless sensor networks has recently been a focal point of research, meanwhile with many research challenges. The major challenges include the problem of high conflicting information fusion processing and the requirement for light-weight algorithms with low computational complexity. In the paper, an evidence reasoning method based on the logic expression, namely DSlT, is proposed. By definition of the new combination rule of evidence based on the logic operation and by strict reservation of local conflict, DSlT deals with high conflicting information fusion. By defining new focal elements, the combination amount of focal elements is lowered greatly. Accordingly, the computation cost is reduced dramatically. To verify the performance of DSlT, we conduct two experiments. The first example experiment shows that our approach can effectively deal with high conflicting information fusion. Additionally, compared with DSmT, the computation cost of DSlT is reduced by 81.08% in the process of 3-dimensional evidence fusion. In the real scene experiment, vehicle classification is the application background. The traffic information acquisition platform based on an image sensor network is used for collecting image data of vehicles. The comparison results further indicate the efficiency and advancement of DSlT. The experiments fully reveal the potential application prospect of DSlT in the research field of information fusion in wireless sensor networks.