Based on the MgO∶LiNbO3 crystal, the critical phase matching technology and the semi-monolithic cavity structure are used to perform external cavity frequency doubling and generate 532 nm laser. The mismatch of the frequency-doubling cavity modes caused by the thermal lens effect is theoretically analyzed. When the higher fundamental frequency light is injected into the frequency-doubling cavity, the mode matching is performed again to mitigate the effect of mode mismatch on the frequency doubling conversion efficiency. Finally, the frequency doubling process with the maximum frequency doubling conversion efficiency of (49.3±0.45)% is achieved and the corresponding output power is 567.0 mW. Furthermore, the model cleaner can not only improve the 532 nm laser beam quality but also reduce the intensity noise to realize the output power of 470 mW and the beam quality factor of 1.05 for the low-noise green laser, whose shot noise limit is reached at an analysis frequency of 1.65 MHz. The whole frequency doubling system possesses a compact structure, a stable output power, and can supply an effective pump field for the quantum squeezed light source, and thus it can play an important role in quantum precision measurement and quantum information fields.