Labor insurance coverage consists of two types as the following: ordinary injury insurance and occupational injury insurance. In order to judge whether a insured person is injured, sick, incapacitated or deceased owing to an occupational accident or not, the competent central authority prescribed THE GUIDELINES FOR EXAMINING INJURY OR SICKNESS INCURRED ON DUTY (THE GUIDELINES). In this paper, the author first points out the main characteristics and functions of the GUIDELINES article 18 in examining work of job-related accidents, and then seeks the legislative reasons of the GUIDELINES article 18. The author also makes some critical observations on this clause. In conclusion, this paper suggests how to revise this clause.