NOVELTY - Producing liquid hydrocarbon from fraction of hydrocarbon feedstock, comprises (a) pretreating biomass fraction and optionally fraction of another feedstock, (b) combining pretreated biomass fraction and optionally pretreated fraction of another feedstock, (c) performing gasification step, (d) performing conditioning step of synthesis gas, (e) performing recombination of fraction of effluents, (f) washing the effluent with water, (g) eliminating acid gases contained in effluent, (h) performing final purification step, and (i) performing Fischer-Tropsch catalytic reaction step of effluent.    USE - The integrated process is useful for the production of liquid hydrocarbon from a feedstock such as fraction of hydrocarbon feedstock (claimed), for production of biofuel, petrochemical feedstocks, chemical bases and/or hydrogen.    ADVANTAGE - The integrated process ensures efficient and economical production of the liquid hydrocarbon with reduced energy consumption and high production yield and without emission of greenhouse gas.    DETAILED DESCRIPTION - Production of liquid hydrocarbon from a fraction of hydrocarbon feedstock containing at least one biomass fraction and optionally at least one fraction of another feedstock, comprises (a) pretreating the biomass fraction and optionally the fraction of another feedstock by (a1) drying, (a2) roasting and (a4) grinding, (b) combining pretreated biomass fraction and optionally pretreated fraction of another feedstock, (c) performing gasification of effluent and/or pretreated fraction and optionally fraction of another feedstock directly introduced in an entrained flow reactor, (d) performing conditioning step of synthesis gas by washing a first part and a additional part with water and fractionation of the synthesis gas into two effluents, eliminating halogenated compounds by (d1) passing the first part to at least one guard bed, (d2) converting carbon monoxide to steam formed on the effluent and (d3) catalytically hydrolyzing carbonyl sulfide compound and hydrogen cyanide compound contained in the additional part of the effluent to hydrogen sulfide and ammonia, (e) performing recombination of at least one fraction of each effluents, (f) washing the effluent with water to eliminate impurities such as ammonia and hydrogen chloride, (g) eliminating acid gases (carbon dioxide and hydrogen sulfide) contained in effluent by chemical or physical solvents, (h) performing a final purification step to at least one guard bed for adsorbing the trace impurities such as hydrogen sulfide, carbonyl sulfide, ammonia and hydrogen cyanide remaining in the synthesis gas, and (i) performing Fischer-Tropsch catalytic reaction step of effluents. An INDEPENDENT CLAIM is included for an installation for production of liquid hydrocarbon from a fraction of hydrocarbon feedstock, comprising a feedstock pretreating unit comprising a drying unit, a roasting unit, optionally granulating unit and a grinding unit, optionally a combining unit comprising a conduit, a gasification unit comprising the entrained flow reactor, a synthesis gas conditioning unit comprising a washing unit, a guard bed, a catalytic hydrolysis unit and a recombining unit, a washing unit, an eliminating unit, a final purifying unit, and a Fischer-Tropsch synthesis catalytic reaction unit.