A dual-wavelength continuous-wave deep-red laser based on an a-cut Pr3?:YLF crystal pumped by a 444 nm blue la-ser diode is experimentally demonstrated. In a compact two-mirror linear cavity, no additional intracavity wave-length-selective element is introduced; instead, simultaneous oscillation at 698 nm and 720 nm is realized by opti-mizing the reflectivities of the output coupler at these two wavelengths and employing a short-cavity configuration. The gain balance and coexistence mechanism of the two deep-red spectral lines in the a-cut Pr3?:YLF crystal are an-alyzed in terms of the dual-wavelength oscillation threshold condition, mode competition, and spatial hole burning effect. Experimental results show that stable simultaneous laser emission at 698 nm and 720 nm is achieved under dual-wavelength operation, with a total output power of 102 mW. The maximum output powers at 720 nm and 698 nm are 78 mW and 24 mW, respectively. The power fluctuation over 30 min is 2.19%, and the beam quality factors M2 are 2.34 and 2.64 in the x and y directions, respectively.