From the perspective of serious leisure, this paper explores the effects of serious leisure on marathon runners' running persistence, and the mediating roles of exercise attachment and sport commitment, in order to analyze the psychological mechanism of marathon runners' continuous participation in long distance running and marathon. A total of 326 marathon runners were surveyed using the Serious leisure Inventory, Exercise Persistence Inventory, Exercise Attachment Inventory and Sport commitment Inventory. The included test criteria were that they had participated in long distance running for more than six months and had participated in more than two marathons. The results show that serious leisure can not only directly predict marathon runners' exercise adherence, but also indirectly influence their exercise adherence through two pathways. Serious leisure can influence their exercise adherence through three pathways: the direct predictive effect of serious leisure; The mediating role of exercise attachment; The chain-mediating role of exercise attachment and sport commitment. To some extent, the mediating effect model constructed in this study reveals the internal mechanism of how serious leisure affects marathon runners' exercise persistence, and helps to understand the psychological mechanism of marathon runners' deep involvement in marathon and long-term adherence.