The current research was conducted with the objective of designing and explaining evaluation model of consumers' attitude toward brand extension, and recognition of effective and ineffective factors on the success of this important growth strategy. Research variables were measured through two pretests and a main test, utilizing three questionnaires. Making sure the measurement tool is reliable and valid, it was distributed among a sample composed of 384 shoppers of home appliances in the three main markets of home appliances, through exploratory and confirmatory factor analysis methods. The approach used in the current research was survey-correlation and definitely based on the structural equations. Finally, the comprehensive model of brand extension demonstrated that the perceived fit, perceived quality and the power of the parent brand had an effect on the consumers' evaluation. Also, the impact of involvement on brand extension as a moderator variable was confirmed.