Raman spectra of the typical chemical vapor deposition (CVD) synthetic diamonds were compared when excited with 405, 532, and 785 nm wavelengths, respectively, at room temperature. The results show that: 1) at the same excitation wavelength, the Raman peaks corresponding to the intrinsic structure or optical defects become more obvious with the increase of laser power, and the corresponding peak positions do not shift with the increase of laser energy. Moreover, there are some spectral differences even though these diamonds all belong to the type II, including the occurrence characteristics of impurity elements and the methods of treatment, which result to some differences for the Raman spectra during these diamonds are excited by the same wavelength; 2) the characteristic of sharp peak locates about 1332 cm^-1 all existed in the Raman spectra of each of diamonds when excited under different wavelengths. Meanwhile, the intrinsic peaks of diamond do not shift with the change of excitation wavelength. On the contrary, the appearance of the optical defects caused by impurities or post-treatment is closely related to the selection of excitation wavelength. This work provides important guidance for the characterization of the structural information of diamond by Raman spectroscopy and the identification of intrinsic peak and optical defect characteristic peak of diamond.