Due to characteristics of service such as intangibility, heterogeneity, and inseparability, the value of service brand is transferred by the interaction between employees and customers. Researchers gradually realize that brand building needs involvement of every member in the corporation and emphasis on internal factors of the corporation such as internal communication, corporate culture, etc. Only several scholars have proposed the concept and opinions about "internal brand building", "internal branding", and "internalize brand", but there is little further research. We perform a longitudinal case study of 1 famous insurance company and find out some important factors of service brand building internally. To find out more valuable information and to confirm our conclusions from the above case study, we perform another 4 semi-structured interviews to 4 representative service companies from information communication, bank, hotel and insurance respectively. After these case studies, we propose the key endogenetic factors of service brand internalization, and construct a conceptual model of service brand internalization. Our work will further the research of service brand internalization and provide an effective instrument for service corporations to improve their brand management