The invention provides a modification method of biomass pyrolysis oil. The modification method of the biomass pyrolysis oil specifically comprises the following steps of: I, demulsification layering dehydration: adding an inorganic salt iron and an organic demulsifier into the biomass pyrolysis oil, wherein the mass ratio of the inorganic salt to the biomass pyrolysis oil is (1:2000)-(1:800), the mass ratio of the organic demulsifier to the biomass pyrolysis oil is (1:4000)-(1:1000), mixing completely, standing and taking an upper-layer biomass pyrolysis oil; II, carrying out catalytic cracking modification on the biomass pyrolysis oil: using a modified catalyst: (1) modified catalyst: carrying out ageing treatment on a zeolite molecular sieve load carclazyte catalyst for 2-8 hours with 100% water vapor at 500-800 DEG C; placing the aged catalyst in a reactor, injecting the biomass pyrolysis oil in a reactor with the catalyst, wherein the agent-oil ratio is 1:(3-16), and carrying out biomass pyrolysis oil catalytic cracking modification at the mass airspeed of 6-15h<1>, the reaction temperature of 380-700 DEG C and the reaction pressure of 0.1Mpa-0.8Mpa.