Abstract:In judicial review, work-related injury identification often employs "reasonable extension" to explain and reason disputed cases, effectively mitigating the conflict between the application of the Legitimacy and RationalityPrinciples. Reasonable extension is an interpretation that follows the principle of purposivene, however, the current regulations on the extent and situations of extension vary, leading to issues such as excessive expansion, restriction, or application deviation in judicial practice, straying from the applicability requirements of the principle of purposiveness. To standardize the interpretation of reasonable extension in judicial review and correct serious damage or excessive protection of workers' rights in work-related injury identification that deviates from the principle of purposiveness, it is suggested in this study to analyze the nature of reasonable extension, clarify the typological distinctions of work-related injury situations attributed to indirect work-related cause under the principle of purposiveness, explore the requirements of work-related cause and specific applicability conditions of reasonable extension under the principle of purposiveness, and explicate dispute scenarios of applicable indirect work-related injury, inapplicable circumstances, or obstructive factors of reasonable extension.