Coincidence effect which occurs in a certain frequency range will impairs the sound insulation of walls. For the purpose to predict the phenomenon of coincidence effect that is unlikely predicted theoretically by the mass law, the Statistical Energy Analysis (SEA) theory are adopted in studying coincidence effect of sound insulation of the light weight single-leaf wall. The comparison among predicted by SEA, by mass law and measured was performed. Therefore, the comparison results show that sound insulation prediction by SEA is more precise and agrees with the measured date. Moreover, the coincidence effect and its effect on sound insulation were predicted by SEA. Eventually, it is likely to select appropriate building materials and configuration to achieve a better sound environment theoretically.