PPMgOLN crystals with a period of 9.8μmwere fabricated on 5% MgO doped lithium niobate wafers by pulse voltage polarization method. Nd∶YVO4 crystals that pumped with 808 LD are adopted with the linear flat cavity structure and optimal coating scheme. By accurately controlling the temperature,the dual wavelengths of 1064 nm and 1342 nm are operated,and the 593 nm yellow light output is realized through the quasi phase matching of the sum frequency in the polarized crystal. When the pump power is 3 W,the maximum output of sum frequency light is 255 mW of 593 nm laser,and the optical to optical conversion efficiency is 8.5%,with the output power fluctuation is less than 2% within 1 h.