The amount of audit effort and, consequently, audit fee of companies is affected by the type of Business strategy. A review of the business strategy and its relation to auditors' efforts in the context of Standard No. 11 of the Audit Supervisory Board refers to the need for auditors to have adequate knowledge of the business and industrial environment of the Client for the planning of the audit work. In this regard, the main objective of this research is to investigate the relationship between the type of business strategy of the Client and the audit fee of the companies. Following the researches of Mills and Snow (1978, 2003), in this research, indicators of capital intensity, renovation of property and equipment, overhead efficiency and financial leverage were used for determining the type of Client business strategy (aggressive strategy and defensive strategy). The statistical population of this research is the companies accepted in the Tehran Stock Exchange during the years 1387 to 1394 and the sample size is 680 observations (year-company). The results of the data analysis show that there is a positive (direct) correlation between the Client's aggressive strategy and the audit fee. These results also show that the aggressive strategy has a more positive correlation with audit fee compared to the defensive strategy.