The coal fast pyrolysis/circulating fluidized bed combustion/catalytic reactor coupled fractionation conversion process is easy to operate and maintain, with significant economic benefits, which is one of the effective ways to achieve clean and efficient utilization of coal resources. However, due to the poor tar quality and high pollution element content produced by the rapid coal pyrolysis process, the catalyst is frequently deactivated and regenerated. Therefore, a cheap and efficient non regenerative catalyst has been prepared in this paper. The effects of calcination temperature and modification method of catalyst on the catalytic cracking characteristics of coal tar were investigated in a fixed bed catalytic reactor with low-temperature coal tar as raw material and natural dolomite as research object. The 1% Ni/2%Fe dolomite catalyst was prepared under the optimum preparation conditions, and the effect of reaction temperature on the catalytic cracking of coal tar was investigated. The results show that with the increase of calcination temperature, the main components of dolomite, such as CaCO3 and MgCO3 is promoted to convert into CaO and MgO active substances, and the activity of natural dolomite catalyst gradually increases and tends to be stable, with the optimal calcination temperature of 750 ℃. The cracking of tar is not promoted by introducing Fe alone, but the catalytic activity of natural dolomite catalyst is significantly improved by introducing Ni and Fe at the same time. The best modification method is 1% Ni/2% Fe dolomite. The introduction of Fe as a promoter protects the sulfur poisoning deactivation of the active component Ni, while the introduction of Ni and Fe alleviates the sintering phenomenon of the catalyst. Fe can be used as an auxiliary agent to slow down the generation of carbon deposits in the catalytic process. The dolomite catalyst modified by Ni promotes the cracking of aliphatic compounds and sulfur-containing compounds. Indene and naphthalene compounds do not undergo cracking reactions, but products such as hydroindene and hydronaphthalene appear.