The evaluation of web software trustworthiness is an urgent issue to tackle in the background of internet and information society. In this paper ,the Multiple Attribute Group Decision Making model for Web Software Trustworthiness (WST-MAGDM) is established: first, the ISO/IEC 0126 and web software attributes diagram is chose as the basic models and the simple web software trustworthy model as the contrast model, then ,the model is improved by using Principal Component Analysis (PCA) to questionnaire survey; second, the model is the foundation for building the web software comprehensive evaluation index system and evaluation grading criterion; finally, combing subjective and objective weighting methods in group decision-making, this paper can evaluate web software trustworthiness. Selecting planning-deployed internet banking from a bank in China can provide reference for enterprise decision-maker according to the decision rule set.