Abstract: In view of current high noise of domestic 561 nm laser, affecting its practicality, 561 nm yellow laser with high stability and low noise is proposed. Nd:YAG crystal is used to obtain 1 123 nm fundamental frequency light, and output of LBO crystal is 561 nm. Threshold pump power of 1 112 nm, 1 116 nm and 1 123 nm wavelength is analyzed theoretically, and a single wavelength oscillation condition of 1 123 nm is proposed to determine requirements of resonant cavity coating. According to theoretical calculation, a reasonable resonant cavity system is designed, and single-wavelength oscillation of 1 123 nm line is realized by suppressing oscillation of 1 112 nm and 1 116 nm lines in the resonator. At a pump power of 5 W, 561 nm laser single wavelength output is achieved with an output power of 107 mW, power instability of 0.7% and noise of 1.2%.