Abstract: Three kinds of organic molybdenum catalysts: molybdenum catalyst without sulfur (CAT-MoI), powder molybdenum catalyst with sulfur (CAT-MoII), and oily molybdenum catalyst with sulfur (CAT-MoIII) were synthesized. The performance of these catalysts in residue hydrocracking was investigated in an autoclave at the initial H2 pressure of 7MPa,430 ℃. The results show that the inhibition of coke formation enhances in the order of CAT-MoI＜CAT-MoII＜CAT-MoIII. To explore the cause for the difference, CAT-MoI, CAT-MoII, CAT-MoIII were dispersed in VGO and sulfurized at the conditions of initial H2 pressure of 7 MPa, 375 ℃for 60 min, respectively. XRD、TEM、SEM and Melvin Dynamic Light Scattering（DLS）were used to characterize the metal sulfides separated from VGO. The characterization results show that the metal sulfides from CAT-MoIII display the highest dispersity, lowest crystallinity and smallest particle size. The CAT-MoI has the highest crystallinity and the largest particle size.