A 589 nm yellow laser is developed for dermatological applications by single-pass frequency doubling of a linearly-polarized narrow linewidth 1178 nm Raman fiber laser in a periodically poled MgO-doped near-stoichiometric LiTaO3 crystal. Up to 6.4 W continuous-wave 589 nm laser is obtained with a conversion efficiency of 14%. The wavelength flexible cascaded Raman fiber laser combined with the single-pass frequency doubling device has advantages of small volume, low cost and easy operation. This device is very suitable for use in the medical field. By optimization, the expected power can be further improved.