According to the domestic studies conducted on in the field of internal controls, the gap of providing models for identifying weak internal controls is felt completely. The present study is aimed at providing a model for assessing the quality of internal controls based on the characteristics of the economic unit, the characteristics of auditor as well as their expected goals in the Firm's listed in Tehran Stock Exchange. This model is designed according to quantitative criteria. To achieve the research’s goal, 86 Firm's from all Firm's accepted in Tehran Stock Exchange for the period 2012-2017 were selected and the research hypothesis was tested using the combined data approach. Given the research hypothesis that points out that the internal assessment model based on the characteristics of the economic units, the characteristics of auditor and their expected objectives may more accurately assess the quality of the internal controls, according to the significance level of less than 0.05, the independent variables indicate a significant relationship between the internal controls assessment model based on the characteristics of the economic units, the characteristics of auditor and their expected objectives as well as the weaknesses of the internal control of the Firm. Furthermore, the estimated coefficient of the control variables of the research indicates a significant relationship between these variables and the weaknesses of the internal controls.