With the continuous development of artificial intelligence technology, digital human technology offers extensive applications in science popularization education. This paper designs an AI popular science digital human system using local private large model technology, which integrates key technologies including speech recognition, natural language processing, speech synthesis, and digital human driving to enable intelligent interactive Q&A with users. The system adopts a locally deployed architecture, fine-tuned based on the Qwen large language model, and combines SenseVoice speech recognition, CosyVoice speech synthesis, and the LiveTalking digital human driving engine to build a complete popular science interaction process. The system has been put into practical use in scenarios such as science and technology festivals in primary and secondary schools and science and technology exhibition halls, which effectively improves the fun and interactivity of science popularization education and provides a new solution for cultivating scientific literacy among teenagers.