Herein, an intracavity single-longitudinal-mode 593.5 nm yellow lasers with compact structure, stable performance, and low cost is designed. A laser diode end-pumped Nd∶YVO4 crystal is used to produce 1064 nm and 1342 nm dual-wavelength laser beams with a linear flat-cavity structure. The intracavity sum-frequency mixing of the 593.5 nm continuous yellow laser output is achieved via KTP Ⅱ-type critical phase matching. The Brewster plate (BP) and sum-frequency crystal KTP are used as a birefringent filter for frequency selection. When the pump power is 5.0 W, the single-longitudinal-mode output power at 593.5 nm is 30 mW, root-mean-square noise is 0.8%, and line width is 150 MHz. For this condition, the fundamental light at 1064 and 1342 nm is detected to be in the single-longitudinal-mode state. Experimental results show that the single-longitudinal-mode sum-frequency laser is achieved using the birefringent filter technique for a loss of more than 1.5% for the adjacent fundamental mode.