Synthesized organic gelling agent (Gn) and gaseous silica (SiO₂) were used to prepare corresponding gelled hydrocarbon fuels with four kinds of high density liquid fuels HD-01, HD-03, HD-03-I and QC respectively. The minimum addition amount of gelling agents required was studied.The basic physical propertiessuch as density, viscosity, heat value for Gn and SiO₂ gelled fuels were determined. Their thermal stability, centrifugal stability, long-term storage perforemance and other stability properties, as well as rheological properties were also investigated. Results show that at least 6% SiO₂ was added to make the liquid fuel form the gelled fuel, while addition amount of Gn required for gelling the fuels is not greater than 1% with little influence on the density and heat value of the fuel itself. No liquid exudation phenomenon happens after Gn galled hydrocarbon fuels are stored at -40 ℃, room temperature or high-speed centrifugation. The viscosity of Gn gelled hydrocarbon fuels decreases significantly with the increasing shear rate, approaching the viscosity of liquid fuel at high shear rate. By scanning electron microscopy,it is found that Gn can be self-assembled to form a three-dimensional fiber network structure in fuel, which can be damaged by stirring or high temperature (150 ℃) and recovered by static or cooling, making the rheological and thixotropic properties of Gn gelled hydrocarbon fuels significantly better than those of SiO₂ gelled hydrocarbon fuels and more conducive to pipeline transportation and atomization.