In the face of the decline of time-honored brands, activating time-honored brands by means of product extension is an effective guarantee for the long-term development of time-honored brands and an important way for them to achieve lasting success. In this paper, Ye Chun Tea House is taken as the parent brand. Through consumer testing sashimi buns and hamburger are identified as two extension products with significant differentiation degree of perceived fit with the parent brand. Student’s t test and multiple regression analysis were used to explore the positive or negative impact of extension products with different perceived fit on brand, as well as the effect of perceived fit on brand attachment and brand loyalty. The cross-multiplicative model is used to discuss the strength of the above influence in different gender, age and income consumer groups. The empirical analysis and research conclusions of this paper focus on two aspects: first, extension products with high perceived fit improve brand loyalty, while extension products with low perceived fit reduce brand loyalty. Second, for extension products with high perceived fit, perceived fit positively affects brand loyalty. Brand attachment plays a mediating role between perceived fit and brand loyalty. Age had a negative moderating effect on perceived fit and brand attachment, perceived fit and brand loyalty, while income level only had a positive moderating effect on cultural fit and brand attachment, cultural fit and brand loyalty. Based on the research conclusions, this paper provides policy-making advice for government departments in four aspects: research and development of new products, optimization of financing services, loose loan policies and construction of omni-channel marketing platform.