The solid-state lasers in the yellow-orange region of the spectrum have a variety of promising applications in biomedical diagnostic (based on fluorescence detection) and display. Operation of a high efficient 599 nm yellow-orange Raman laser with a Ba(NO₃)₂ crystal in the external Raman cavity pumped by the harmonic of Nd∶ YAG laser (532 nm) was reported. Barium nitrate crystal was grown by the aquasolution cooling method with the length of 48 mm long. To achieve conversion efficiency about the theoretical limit,the parameters of pump laser and external Raman cavity were optimized. The Raman cavity was composed of diachronic mirrors with optimal reflectivity for the second Stokes wavelength. The use of the external cavity with optimal reflectivity output coupler reduced the threshold pump intensity and increased overall efficiency with respect to single pass cell. The second Stokes Raman laser' s pulse compression phenomenon and two little peaks temporal behaviour were recorded and analysed. When the pump laser was operated at laser power of 4.1 W,the maximum second Stokes Raman output power of 710mW was obtained with FWHM of 1.1 nm at output wavelength of 599.38 nm,and the maximum conversion efficiency of 17.5% was observed. The slope efficiency was calculated as 24.8%.