In recent years, the dual optical comb technique has become a hot topic in the field of scientific research due to its ultra-high frequency resolution and detection accuracy. In this paper, the methods of generating dual-combs using electro-optical modulation, micro-resonator, two phase-locking independent mode-locked lasers and single-cavity dual-comb laser are introduced respectively. The advantages of the dual optical comb generation method based on single-cavity dual wavelength laser, such as high integration, simple structure and low cost, are emphasized. After that, the working principle and the latest research progress of the multiplexing methods for the dual-wavelength operation in single-cavity dual comb lasers, such as pulse waveform multiplexing, space multiplexing, direction multiplexing, wavelength multiplexing and polarization multiplexing are described in details. Finally, the applications of single-cavity dual optical combs in spectroscopy, ranging, fiber sensing and other fields are presented, and future research and development directions of single-cavity dual-combs are prospected, which can provide reference for promoting the further improvement of technical performance and wide application of single-cavity dual-optical comb.