This paper analyses the seabed reflection coefficient of the "geoacoustic model" of continental terrace in shallow water, which includes two kinds of parametres:the "type parameters" and the "structure parameters". For small grazing angle, the "structure parameters" become nonsensitive in a certain band of sound frequency and the reflection coefficient is determined by the "type parameters".However, the former are sensitive for "low sound speed" sea floors. For large grazing angle, the "structure parameters" affect sound reflection character greatly.