Abstract: Sound scattering is important in computer simulation of geometric room acoustic modeling.The scattering on room boundaries can not be fully characterized only by a single-valued scattering coefficient,therefore the uncertainty of determining scattering coefficient is adopted in modeling.An example of simple rectangular room model is illustrated in this paper with various amounts and dispositions of absorption,and different geometrical complexity of surfaces.The deviations of reverberation time prediction due to the uncertainty of scattering coefficient are investigated by comparing with measurement results.