NOVELTY - Producing olefin compounds having 2-6 carbons and aromatic compounds from liquid feedstock of bio oil, comprises: hydroreforming feedstock in presence of hydrogen and hydroreforming catalyst comprising transition metal and carrier e.g. silica; hydrotreating organic phase in presence of hydrogen and catalyst with hydrogen/hydrocarbon of 100-3000 Nm3/m3; hydrocracking in presence of hydrogen with volume ratio of hydrogen to hydrocarbon of 120-200 degrees C, recycling a portion of fraction with initial boiling point of 120-200 degrees C to hydrocracking; and steam cracking fraction containing naphtha.    USE - The process is useful for producing olefin compounds having 2-6 carbons preferably ethylene, propylene or butadiene and aromatic compounds preferably benzene, toluene and xylene/ethylbenzene, from liquid feedstock comprising at least one bio oil, preferably liquefied biomass from pyrolysis of biomass.    ADVANTAGE - The process: provides aromatic compounds with less quantity of impurities; provides the olefin compounds and aromatic compounds with increased yield; and reduces investment costs and operating costs.    DETAILED DESCRIPTION - Producing olefin compounds having 2-6 carbons and aromatic compounds, from a liquid feedstock comprising at least one bio oil, comprises: introducing the feedstock in a first stage hydroreforming in the presence of hydrogen and a hydroreforming catalyst comprising at least one transition metal comprising groups 3 to 12 and at least one carrier comprising active carbon, silicon carbide, silica, transition aluminas, silica aluminas, zirconium oxide, cerium oxide, titanium oxide and/or the transition metal aluminates to obtain at least one liquid effluent comprising at least one aqueous phase and at least one organic phase, operating at 200-380 degrees C at an absolute pressure of 3-30 MPa, at an hourly space velocity of 0.1 and 5 hour-1; processing in a second hydrotreating step of at least a portion of the organic phase from the effluent from the first stage in the presence of hydroreforming hydrogen in at least one reactor containing a hydrotreating catalyst, operating at 250-400 degrees C at a pressure of 2-25 MPa, at an hourly space velocity of 0.1-20 hour-1 and with a total amount of hydrogen mixed with the feedstock such that the hydrogen/hydrocarbon is 100-3000 Nm3/m3; processing in a third step of hydrocracking at least a part of the effluent from the second hydrotreating step in the presence of hydrogen in at least one reactor containing a hydrocracking catalyst operating at 250-480 degrees C, under a pressure of 2-25 MPa, at a space velocity of 0.1-20 hour-1 and with a quantity of hydrogen introduced such that the volume ratio of hydrogen to hydrocarbon is between 80-5000 Nm3/m3, where at least a portion of the fraction having an initial boiling point of 120-200 degrees C, separated at the end of the third hydrocracking step is recycled to the third hydrocracking step; separating effluent obtained after the third stage hydrocracking at least one fraction containing naphtha and a fraction having an initial boiling point 120-200 degrees C; introducing at least a portion of the fraction containing naphtha after the separation step in a fourth step of steam cracking to produce an effluent comprising at least one of olefinic compounds having 2-6 carbons, aromatic compounds and hydrogen, operating at 700-900 degrees C in the presence of steam injected in a weight ratio to the incoming fraction containing naphtha of 0.2-2.