Highly effective frequency doubling conversion of continuous wave, single frequency 1064 nm fundamental laser is realized based on the Pound-Drever-Hall extra-cavity frequency doubling technique. When the length of the ring frequency doubling cavity is accurately locked, the green laser output with the highest power of 8.73 W is obtained with the use of the type I noncritical phase matching lithium triborate crystal and the frequency conversion efficiency reaches 68.9%. Based on this, the green laser wavelength locking and tuning characteristics are investigated, and when the root-mean-square value of wavelength locking within 30 min is less than 3 fm, the wavelength is continuously tunable between 532.15 nm and 532.50 nm. The spectroscopic property of the single frequency green laser is measured by the self-heterodyne method, the measured line-width is 18.7 kHz, and the beam quality factor is 1.25 which indicates a superior beam quality.