A design of diode-pumped Nd: YAG laser with a single crystal that generates simultaneous laser action at the wavelengths of 1064 nm and 1319 nm was presented and continuous-wave (CW) of 588.9 nm was obtained for the first time by use of type-I critical phase-matching LBO crystal intracavity sumfrequency mixing. The maximum output power of 62 mW is achieved with an incident pump power of 1.8 W. The optical-to-optical conversion efficiency is up to 3.4%, and the power instability in 24 h is better than ±2.7%. Supported by Hi-Tech 863 project of People’s Republic of China (No. 2002AA311141)