LD side-pumped all-solid-state high-power Nd∶YAG/KTP green laser is reported.The LD pump module at 808 nm provided by the institute of semiconductor,CAS is composed of nine 20 W laser diode arrays,which has maximum pump power of 180 W.When the 3 mm×65 mm Nd∶YAG rod is pumped,using different length of KTP crystal(type Ⅱ critical phase-matching)respectively,the highest power of 21.3 W CW green laser is obtained with 22.5 A pumping current,the power instability is better than 2% and optical-optical(1064~532 nm)conversion efficiency is 42.6%.