Effect of copper compounds on the catalytic activity of n-Bu2SnO in the transesterification of dimethyl carbonate and phenol to diphenyl carbonate was investigated. The results showed that they as promoters could obviously enhance the activity of n-Bu2SnO except for Cu. The characterizations of X-ray diffraction (XRD) identified that CuO could be reduced to Cu, and Cu2O was stable. When the reaction was carried out between 150 and 180 oC, with molar ratio of n-Bu2SnO to Cu2O of 8:1, catalyst amount 0.0067, reaction time 10h, molar ratio of dimethyl carbonate to phenol of 3:1, the phenol conversion and the transesterification selectivity were 60.3% and 99.2%, respectively. In the transesterification, the acid-base synergistic effect between Cu2O as the basic promoter and n-Bu2SnO as the Lewis acid resulted in the active enhancement of n-Bu2SnO. Moreover the performance of Cu2O remained unchanged for seven times reuse.