Abstract: The develpoment of frequency-doubled Nd:YAG laser,consisting of anoscillator,three amplifies,a KTP frequency doubler and etc.,is reported.The system can produce energy higher than 1J at 532nm.It operates at a pulse repetition rate of 1Hz,a pulse width of 6ns～9ns.An energy conversion efficience of 48% for second harmonic generation of 532nm radiation from 1064nm radiation has been achieved.