A Laser diode (LD) side-pumped ceramic Nd:YAG laser was developed to achieve dual wavelength output at 532nm and 660nm, based on LiB3O5 (LBO) intracavity frequency doubling with the method of β-BaB2O4 (BBO) electro-optical Q-switching (EO Q-switching). In the experiment, a T-shaped cavity is designed for laser oscillate to reach the maximum output power of 8.32W at 532nm and 4.2W at 660nm simultaneously; and also, the pulse widths could reach to 88.6ns at 532nm and 96ns at 660nm with the repetition rate of 10kHz. The beam quality factors (M2) could be measured as Mx2=4.36, My2=4.78 at 532nm and Mx2=5.46, My2=5.83 at 660nm. Both the power instabilities of the two output wavelengths are less than 2% in 10h measured at every 1h. All of the EO Q-switching technique, oscillation cavity design and laser gain media, used in this work, illustrate a valid way to develop a dual-wavelength laser with high output peak power.