Audit quality is a multidimensional challenge from both theoretical and practical perspectives. From different perspectives, audit quality can be a function of factors such as auditor’s abilities including knowledge, experience, adaptability and technical efficiency, and professional standards including independence, objectivity, professional care, conflict of interests, and judgement. In addition, probability tree model is one of the common techniques in data mining to solve classified problems. The model is a basis for investigating the probability of the events, and includes four indicators of input, process, context and consequence. The aim of this paper is to investigate the application of probability tree model for audit quality in companies. In terms of methodology, this is a descriptive-analytical study and in terms of goal, this is an applied study. Furthermore, statistical probability model was used in the current study. The statistical population of this study consists of the companies listed on Tehran Stock Exchange in 2010-2015.The results showed that probability tree model is effective in process and consequence of audit quality but the mode is not effective in input and context of audit quality.