Due to the thrive of family businesses in the current economic situation, to solve the problem of the definition of these businesses, in this paper we suggest using a scale that measures the quality of family influence through three dimensions: power, experience, and culture. The family influence on power, experience and culture (F-PEC) scale, as well as strategic planning, have been tested precisely using a random sample of more than 211 people from two companies of Golestan and Shemshal industrial group located in Tehran, Iran through using the confirmatory factor analysis technique. The Scale shows a high level of reliability. F-PEC has been used in a number of studies to theoretical development, particularly in terms of the impact of family influence on the individual resources and as a source of competitive advantage. In this research, strategic planning is also considered as a source of competitive advantage and its impact on the success of the family business has been investigated.