Abstract: Due to the variable and dynamic characteristics in trustworthy software evaluation demands, and to the experts’ subjective decision-making with bounded rationality, to evaluate multidimensional and multi-scale trustworthy software is an important and challenging research. To solve this problem, a trustworthy software evaluation mechanism using utility based evidence theory is discussed and designed. Firstly, a dynamic construction model for trustworthy index tree is defined, including an open index node database and an index tree generation algorithm. So the model can find the correct index system which can reflect the real trustworthy evaluation demands and can be used by trustworthy evaluation agents or users. Secondly, utility theory is used to achieve quantitative and qualitative evaluation information pre-processing, namely, multi-dimension trustworthy evaluation information smooth and consistency transformation. On this basis, a trustworthy software evaluation evidential reasoning algorithm, which can analyze and solve the valuable data from the original information carried by the trustworthy evaluation experts, is given based on distributed evaluation framework and Dempster rule. Finally, the analysis and experimental results of this paper show that the validity and rationality of the proposed method is especially suitable to large scale industrial detection software. It can impel the further research of software trustworthiness evaluation theory under complicated environment.