• Fractional distillation can obviously decrease the O and S content in biocrude. • The majority of the alkali/heavy metals migrated to distillation residue. • Over 35.0% of the As in raw biocrude oil lead to distillation oil. • In-situ catalytic reaction of CaCO 3 /K 2 CO 3 promotes the denitrification process. The high heteroatom and excessive metals induce poor physiochemical properties of algae-biocrude, causing either damage to engine or air pollution. This study systematically investigated elements migration behaviors during vacuum fractional distillation of raw biocrude. Comparing with the raw biocrude, the oxygen (O) and sulfur (S) content in the distillates was greatly decreased by 47.6% and 44.3%, respectively. Over 96.0% of the Ca, K, and Pb in the raw biocrude concentrated into the distillation residue. Notably, the migration morphology of As is very special with only 63.1% of the As migrated into the residue associated with organic As in biocrude. In-situ catalytic reaction of CaCO 3 /K 2 CO 3 may promote the metal migration, denitrogenation, and desulfurization process. The distillate oil obtained at 275 °C (F6) has the highest abundant of saturated hydrocarbon (62.69%) with relatively high H/C and low N/C among all the distillates, which was probably an excellent transport alternative biofuel.