Abstract: As surrogated searchers, elderly people usually entrust others to search online health information. From perspective of surrogated searchers, the paper aims to explore the factor model and hierarchical structure of the elderly's online health information surrogate search behavior, and further to reveal its influence and correlation path and provide reference for optimizing the elderly's online information search behavior.A semi-structured in-depth interview is conducted with 26 elderly people. The interview data are coded and classified by grounded theory. The level and correlation of the influencing factors of the elderly's online health information surrogate search behavior are divided and constructed by interpretive structure model. The results show that there are four main categories, including health status, emotional needs, information literacy and self-cognition, all of which influence online health information surrogate search behavior of the elderly. Moreover, seven categories constitute factor model and hierarchical structure of influencing factors of the elderly's online health information surrogate search behavior, which is divided into the appearance layer, the key layer and the root layer. Specifically, information search ability and health status are the deepest and most fundamental factors that trigger the elderly's online health information surrogate search behavior, and they affect the elderly's online health information surrogate search behavior through information value judgment, self-efficacy and emotional needs. The paper enriches and perfects the research on the online information search behavior of the elderly.

Key words: Information search of the elderly, Surrogate search, Online health information seeking, Grounded theory, User behavior, Information service