The n-heptane content in the platinum reforming raffinate (93-102°C) fraction was more than 57%. The n-heptane was adsorbed in the vapor phase by a 5A molecular sieve, and then was desorbed by steam to separate n-alkanes. Nickel-catalyzed hydrogenation converts a small amount of normal olefins into n-alkanes, and the iodine value is reduced to 0.1 g iodine/100 g or less. At the end of the distillation, standard n-heptane with a purity of 99.9% was obtained. Industrial grade n-heptane purification can also be used concentrated sulfuric acid washing, methanol azeotropic distillation and other methods.