In order to study the effect of hydrocarbon group composition on physical and chemical properties of jet fuel, the coal?based kerosene and biogenic aviation fuel were added to No.3 jet fuel respectively, and the seventeen physical and chemical properties of jet fuel were tested according to the experimental methods specified in GB 6537—2018《Jet Fuel No.3》. The results showed that hydrocarbon group composition was the primary factor affecting 8 physicochemical properties of blended jet fuel. As the mass fraction of paraffin increased or the mass fraction of naphthene decreased, the 10% recovery temperature, 50% recovery temperature, final boiling point, freezing point, kinematic viscosity at -20 ℃, and smoke point generally decreased monotonically, while density and net calorific value per volume increased monotonically. Hydrocarbon group composition was a non?primary factor affecting the remaining 9 physicochemical properties. An increase or decrease in paraffin mass fraction led to a decrease in flash point and naphthalene hydrocarbon volume fraction, whereas paraffin and naphthene mass fractions had negligible effects on net calorific value per mass, corrosiveness, thermal stability, gum mass concentration, water reaction interface condition, water reaction separation degree, and water separation index. When blending aviation alternative fuels with traditional jet fuel, the physicochemical properties of the blended fuel can be predicted to a certain extent based on the influence rules of hydrocarbon group composition on jet fuel properties, thereby reducing experimental trials and improving efficiency.