It is essential for enterprises to adjust brand positioning according to the changes of target customers for sustainable development. The growth of instrumental internet products (internet Apps) presents obvious stages. From providing free tools (to generate more traffic) to becoming a platfbnn, the connotation of instrumental internet products has changed explicitly. Exploring the growth stages and positioning of internet applications in different stages could help us understand the evolution characteristics of internet App brand positioning and provide inspirations for such enterprises to actively adjust brand positioning for sustainable growth. In addition, this paper explores how internet App brands ( bom and developed in the social media context) apply communication strategies to establish brand positioning, which provides a useful reference for enterprises to improve the efficiency of applying social media. This research was based on the analysis of brand management practice of Youdao dictionary in 2007-2020. Finally, this study have the following findings: (1) the internet App brand positioning should actively evolve with different stages of enterprise development. Specifically, the initial period, the developing period and the extension period are suitable for adopting functional positioning, symbolic positioning and emotional positioning respectively and aiming at core customers, peripheral customers and extensive customers respectively to estahlish a brand image in line with the objectives of the brand stage to realize the development path of "tool-content/community-platform" ； (2) enterprises should set up appropriate communication goals according to different stages of brand positioning, select and match communication tools with the guidance of communication objectives in the social media context, and evaluate communication effects based on communication objectives. These findings contribute to the adjustment of brand positioning to achieve long-term development and the improvement of social media communication efficiency for the internet Apps.