Current research by considering key condition of business strategy in organizational decision and its importance is willing to trace the effect of product market competition and companies' life cycle on their elective business strategy. Along that, data of 115 listed sample companies in Tehran Stock Exchange was gathered along 2013 to 2018 years and hypothesis model was tested with the help of multiple regression analysis. The criteria to assess the business strategy was Ittner & Larcker (1997) model and Herfindahl-Hirschman Index to product market competition and in the last, the base for distinguishing the sample companies upon their life cycle stages was Anthony & Ramesh (1992) model. The findings indicate that product market competition has a significant impact on business strategy and those companies which are operating in high competition condition have tendency to defensive business strategy. Besides, company's life cycle stages has also a significant impact on selecting business strategy and those companies which are in growth life stage in compare to others (those operating in maturity and decline stages) have more tendency to gain of offensive business strategy. high competition condition in product market gets reducing tendency of growth life stage companies to applying of offensive business strategy. Finally new companies have tendency to opportunistic business strategy while, old ones desire to use Analytical business strategy.