The invention relates to a low-temperature 
isomerization method for low-carbon normal alkanes, wherein the low-temperature 
isomerization method includes the following steps: (1) carrying out heat exchange of a light 
hydrocarbon raw material containing normal C5 and normal C6 as principal components with an 
isomerization product, and after heat exchange, rectifying to obtain heterogeneous C5, normal C5 and a heavy 
hydrocarbon; (2) rectifying the heavy 
hydrocarbon again, to obtain heterogeneous C6 and a heavy hydrocarbon, mixing the normal C5 with the heavy hydrocarbon, and then supplementing 
chlorine; (3) carrying out 
drying dehydration on the material obtained after 
chlorine supplement, mixing with dried fresh 
hydrogen and circulating 
hydrogen, heating, and carrying out an isomerization reaction under the action of a catalyst after heating; and (4) after carrying out heat exchange of the isomerization product with a fresh 
raw material, carrying out first gas-liquid separation, wherein the obtained non-condensable gas is circulating 
hydrogen; and carrying out gas-liquid separation on the obtained liquid again, mixing the obtained liquid with a fresh 
raw material, and then rectifying. The yield of the 
liquid product obtained by the low-temperature isomerization method is more than 98%, the isomerization rate is 60%-90%, and the 
octane value can be increased by 10-30.