There are many evidences for legal reasoning, and the evidence can only support assertion or fact partly. The main job for the jury is to draw the final conclusion with these evidences. To assess and improve the reliability of the final conclusion, the paper proposes a method to fuse the legal evidences based on Dempster-Shafer evidence theory. The method assesses the reliability of evidences at first, and then fuses them with D-S combination evidence theory to draw a final conclusion. The paper expands how to use the method with an example. There are three kinds of evidences in a law case: witness, circumstantial evidence, and authentication, with the introduction of D-S combination theory, three evidences are fused, and then the reliability of the final decision can be assessed.