Brand equity,a core content of brand theory,refers to the value brand adds to product.Brand extension means the new business field an enterprise enters or new product the enterprise presents on the basis of the current brand.Brand equity is the basis for the new business and product and different brands have different extensions.Brand extension relates to what can be transferred into the new extended product in the present brand equity.Attention should be paid to the following aspects when brand is extended: the attitude of customers towards the present brand,the adaptability between the present brand and extended brand,the consistency of brand images,and the dilution of the present brand.