Abstract: The effects of dispersed catalyst and hydrogen donor on the cracking and cracking selectivity of characteristic model compounds in residue oil, such as N-eicosane, butyl benzene and 1,6-diphenylheptane, were investigated in the thermal, hydrothermal and catalytic hydrocracking systems at 440 ℃. The three compounds had different cracking characteristics. N-eicosane had the simplest bond-scission way. The bond-scissions of butyl benzene in the thermal system were mainly β- and γ- bond-scission, while β- in hydrothermal and α- bond-scission in catalytic hydrocracking were main reactions. 1,6-diphenylheptane had more complex cracking ways, which were α-, β-, homolysis and γ-bond-scission. The bond-scissions of 1,6-diphenylheptane in thermal cracking underwent such four ways, how-ever, α- and β-bond-scission or α-bond-scission were main reactions in hydrothermal or in catalytic hydrocracking of 1,6-diphenylheptane, respectively. It seems that these three model compounds experienced the radical reaction in the single systems of model compounds or in the binary system of model compounds/tetralin for thermal, hydrothermal and catalytic hydrocracking. Molecular hydrogen as well as dispersed catalyst enhanced the cracking of model compounds, while H-donor depressed the cracking. For cracking selectivity of the three compounds, thermal and hydrothermal cracking were the basis of other processes and dispersed catalysts clearly affected the cracking selectivity of alkyl aromatics. On the other hand, hydrogen donor had influence on a certain extent on the cracking selectivity on the basis of the thermal, hydrothermal and catalytic hydrocracking systems.