Paraffin fuels are ideal energy for hybrid rocket engine owing to the characteristics of high regression rate. In order to study the relationship between the combustion characteristics and chemical components of paraffin fuel, the gas chromatography was carried out for 54^#, 58^#, 62^# and 66^# 4 kinds of macrocrystalline paraffin fuels, and measured the combustion heat and the regression rate in the oxygen flow rate of these 4 kinds of macrocrystalline paraffin fuels. In addition, the energy characteristics of these macrocrystalline paraffin fuels at different oxygen fuel ratio were calculated using NASA-CEA software. The results show that the average molecular formulas of the 54^#, 58^#, 62^# and 66^# 4 kinds of macrocrystalline paraffin were C_26.40H_54.80, C_27.59H_57.18, C_28.02H_58.04 and C_32.11H_66.22, respectively, and the percentage contents of the n-alkanes of the 54^#, 58^#, 62^# and 66^# 4 kinds of macrocrystalline paraffin were 92.79%, 89.44%, 88.36% and 84.55%, respectively. The bigger the carbon number as well as the less the percentage content of n-alkanes, the smaller the combustion heat of paraffin fuel. And the regression rates of paraffin fuels were reduced along with the increase of carbon number. According to the calculated results of NASA-CEA software, the theoretical specific impulse of paraffin fuels were decreased with the carbon number of paraffin increasing, and the adiabatic flame temperatures were increased with the carbon number of paraffin increasing, but these influences of the chemical components of paraffin fuels on the energy characteristics were insignificant. The optimum oxygen fuel ratio of 4 kinds of macrocrystalline paraffin were all 2.7, the theoretical specific impulse were all about 354 s more than HTPB, and the adiabatic flame temperature were all about 3600 K less than HTPB.