Due to the sharp increase of customer acquisition cost of public domain traffic, more and more businesses are endeavoring to the private domain traffic in order to achieve performance breakthrough, but have yielded little by now. When relationship marketing enters the era of private domain, the extant literature shows no clear conclusions on how to realize a good brand-customer relationship and how to change the corresponding marketing strategy. Thus, based on the related theories of B2C relationship marketing, the relationship between brand employees'' self-disclosure behavior, relationship quality and customer loyalty under the private domain operation mode was investigated through interviews and questionnaires. The findings suggests that brand employees'' self-disclosure positively affects the relationship quality under the private domain operation mode; Relationship quality positively affects customer’s employee loyalty, and then positively affects customer’s brand loyalty; There are moderating effects of relationship strength and gender in the impact of brand employees'' self-disclosure on relationship quality. The research conclusion is helpful for businesses to make full use of employees'' self-disclosure behavior through the private domain platform to give play to the advantages of the private domain operation mode and improve the outcomes of relationship marketing.