Abstract: The medium temperature pyrolytic coal tar was used as raw material and was analyzed, in which the fraction with boiling point > 350 ℃ that contains the resin of 30.88%, the asphaltene of 37.27% and the tetrahydrofuran insolubles of 3.36% is difficult to hydrocrack directly by conventional fixed bed. A Mo-based ultra-dispersed catalyst was synthesized, and characterized by FT-IR, XPS, XRD, SEM and TEM, etc. The catalyst contains Mo=O and Mo-S characteristic structure and has an excellent dispersibility in the reaction system, and the vulcanization ratio of molybdenum reaches 84.34%. The catalyst can be decomposed into hyper dispersive MoS₂ particle in the reaction system. The suspension bed hydrocracking experiments were carried out in a 0.25 t/d continuous unit with heavy fraction of tar. Moreover, the effects of reaction conditions on product distribution and coking rate were investigated. The optimum reaction conditions were 19 MPa, 440 ℃ and 300 mg/kg of catalyst addition. Under these conditions, the naphtha yield is 24.47%, the diesel fraction yield is 49.71%, and the coking rate is 1.32%.