Brand extension is the most popular marketing strategy; such a shortcut is often seen as beneficial because of the high trade pressure, increased introduction costs, high failure rate of new products, and limited retailer shelf space. The extend profit is to leverage the brand equity to achieve growth while reducing the cost of new product introduction, marketing cost, the risk of new product failure and customers perceived risk. But brand extensions may have the negative associations, cannibalize and dilute the brand value and the underexploited ideas of new products. From the literature review, we propose the key successful factors of brand extension for the firms to reduce the possibility of extension failure.