To improve pyrolysis efficiency and tar quality, the effects of different amounts of additional molybdenum disulfide (MoS2) on the microwave pyrolysis of low-rank coal under the circulating gas atmosphere were studied in a coal gas microwave co-pyrolysis experimental apparatus via self-research and development. Coal gas analyzer, X-ray diffraction, combined scanning electron microscopy and energy-dispersive spectrometry, Fourier transform infrared spectroscopy, and gas chromatography mass spectrometry were all used to conduct analysis and characterization of the pyrolysis products. The experimental results showed that both the yield of liquid products and valuable component (H-2 + CH4 + CO) in the gas increased initially and then decreased with the increase of MoS2. When the optimum addition ratio of 8.3% MoS2 was selected, the yield of liquid products and light oil content were up to 28.4 and 67.55%, higher by 7.6 and 49.48% compared to those of non-MoS2, respectively. The gas heat value was up to 15.14 MJ/m(3), and the contents of CH4, CO, and H-2 were 25.34, 31.51, and 22.19%, respectively. The valuable component content in the gas was up to 79.04%. The ash content in bluecoke (i.e., solid product) was higher by 11.23% compared to that of non-MoS2, and the n(H)/n(C) value increased by 0.8%. The contents of alkanes and single-ring aromatic compounds in the tar increased as well as the n(H)/n(C) values in each of the light, intermediate, and heavy components. It indicated that MoS2 could effectively promote the hydrocracking of coal tar and improve the stability of tar.