This paper presents Fay, a distributed architecture digital human service system that leverages large language models (LLMs) to deliver intelligent and engaging user experiences. Fay seamlessly integrates advanced natural language processing capabilities with lifelike digital human rendering and a modular, scalable architecture. The system’s unique design enables it to understand and respond to user queries, generate human-like responses, and provide personalized assistance across a wide range of applications, including smart agriculture, retail and customer service, and mobile assistants. Fay’s architecture incorporates state-of-the-art techniques for speech recognition, emotion analysis, lip-sync generation, and real-time communication, ensuring a highly interactive and immersive user experience. By harnessing the power of LLMs and combining it with the visual appeal and emotional resonance of digital humans, Fay represents a significant step forward in the development of intelligent, adaptive, and user-centric service systems. We explore its technical foundations, application scenarios, and potential impact on various industries and domains.