Specific requirements and methods of settlement monitoring which were used in bridge of unballasted track passenger dedicated line or high-speed railway are introduced systematically,and mathematical model and determinant conditions of settlement were proposed simultaneously,taking Beijing—Tianjin intercity railway as an example. Specific requirements and methods of settlement monitoring which were used in bridge of unballasted track passenger dedicated line or high-speed railway are introduced systematically, and mathematical model and determinant conditions of settlement were proposed simultaneously, taking Beijing-Tianjin intercity railway as an example.