The basic knowledge of information entropy and unascertained measures are introduced in detaisl. And the evaluation model based on entropy weight and unascertained measure is sets up. We know that it is difficult to determine the weight in the situation of multi-factor. However, it is more credible to use the information entropy to determine the weight, so the problem is solved. At last, the model is applied to appraise a public transit evaluation of one city in Hebei province. The result shows that the model has strong ability to reflect reality.