It is crucial to solve the conflict scale economies and product variety for product family plan. Therefore, from the view of functional parameters and structural characteristics of product family, a strategy was studied to work on product variety optimization and modular platform-based design based on similarity analysis. First of all, PCA (Principal Component Analysis) was performed to identify the key functional parameters. And then, a cluster analysis and a similarity analysis were carried out to provide a similar estimation for the products. Finally, according to the comprehensive analysis it would be helpful to layout the modular platform.