High-power and high efficiency continuous wave green laser has been realized by optimizing the plane-concave-plane resonator of three mirrors in an laser diode side-pumped configuration and KTP of Ⅱ-type phase-matching for frequency doubling. A maximum of 36.6 W continuous wave 532 nm green laser is obtained at pumping current of 36 A, corresponding to optical-to-optical conversion efficiency of 8.71％. The power stability of the laser is measured at output power of 33 W. During a half hour measurement time, the output power instability is 0.27%. The beam transfer factor is less than 8 measured by knife-edge method at output power of 33 W. Astigmatism compensation, misalignment sensitivity and mode profile inside resonator of three mirror folded resonator are also numerically simulated under high pump power.