[Wu, Xiaoning] Chinese Acad Sci, Inst Math, Acad Math & Syst Sci, Beijing 100080, Peoples R China
; [Huang, Chao-Guang
; Sun, Jia-Rui] Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China
; [Wu, Xiaoning
; Huang, Chao-Guang] Chinese Acad Sci, Kavli Inst Theoret Phys China, Beijing 100080, Peoples R China
; [Sun, Jia-Rui] Chinese Acad Sci, Grad Sch, Beijing 100049, Peoples R China
Based on the idea of the work by Wilczek and his collaborators, we consider the gravitational anomaly near a weakly isolated horizon. We find that there exists a universal choice of tortoise coordinate for any weakly isolated horizon. Under this coordinate, the leading behavior of a quite arbitrary scalar field near a horizon is a 2-dimensional chiral scalar field. This means we can extend the idea of Wilczek and his collaborators to more general cases and show the relation between gravitational anomaly and Hawking radiation is a universal property of a black hole horizon.