Abstract: Research on the factors influencing traditional offline learning has reached a high degree of maturity, characterized by stable construct definitions and established measurement pathways. In contrast, online learning remains in a state of rapid evolution as platform functionalities and interaction modes continuously update. The constant emergence of new explanatory variables complicates the selection of relevant factors and hinders the accumulation of comparative evidence across studies. A standardized and scalable hierarchical indicator system for online learning is developed to cover this gap. Key factors rooted in classic learning theories are identified through a combination of deductive reasoning and a systematic synthesis of high-impact literature. A final framework comprising 7 primary, 19 secondary, and 65 tertiary indicators including seven critical dimensions-learners, instructors, instructional design and curriculum, social interaction, evaluation and feedback, technology and platforms, and the external institutional environment--has been established following rigorous boundary definition and consistency validation. The proposed system provides a structured foundation for future empirical measurement and scale development, offering a practical reference for online course design and quality diagnosis.

Key words: online learning, influencing factors, hierarchical indicator system, framework construction