With the rapid development of computer graphics, artificial intelligence, and virtual reality technologies, digital humans have become an essential element in the field of digital media. On short video platforms, digital humans appear as virtual idols, hosts, and educators, interacting with users and providing rich content experiences. However, users' acceptance of digital humans is influenced by various factors, and the specific influence mechanism remains unclear. This study aims to explore the influence mechanism of digital human acceptance among Chinese users in the context of short video animation, focusing on factors such as usage needs, perceived anthropomorphism, and expectation confirmation. Based on the Uses and Gratifications Theory and Expectation Confirmation Theory, this study constructs a conceptual model including usage needs (cognitive needs, emotional needs, integrated needs), perceived anthropomorphism, expectation confirmation, and user acceptance. Through data analysis of 458 valid questionnaires, this study finds that usage needs and perceived anthropomorphism significantly and positively influence expectation confirmation and user acceptance, while expectation confirmation also significantly and positively influences user acceptance. However, the influence of social influence on expectation confirmation is not significant. These results enrich the theoretical research on digital human acceptance, emphasizing the key roles of user needs and perceptions in the acceptance process, and provide new insights into the applicability of social influence in Unified Theory. The findings of this study offer practical guidance for the design and promotion of digital humans in short video animation, contributing to the further development of digital human technology in the field of digital media.