An all solid-state continuous-wave yellow-green laser at 554.9 nm is reported,1342 nm wavelength is obtained from 4F3/2-4I11/2 transition in Nd∶YAG and 946 nm wavelength is obtained from 4F3/2-4I9/2 transition in Nd∶YVO4.Yellow-green laser at 554.9 nm is obtained by using a doubly folded-cavity,type-II critical phase matching KTP crystal intracavity sum frequency mixing by 1342 nm and 946 nm,with incident pumped power of 20 W in Nd∶YAG and 10 W in Nd∶YVO4,TEM00 mode yellow-green laser at 554.9 nm of 1.1 W is obtained at last.The power stability in 4h is better than ±2.8%.