Process to produce olefins from a hydrocarbon stream comprising pyrolysis plastic oil comprising the following steps: a) Providing a hydrocarbon stream containing at least 10 wt % of pyrolysis plastic oil preferably 25 wt %, even more preferably 50 wt %, even more preferably 75 wt %, the other part of said hydrocarbon stream being a first diluent or alternatively providing a hydrocarbon stream containing only pyrolysis plastic oil; b) Optionally putting in contact the effluent obtained at the step a) with silica gel, clays, alkaline or alkaline earth metal oxide, iron oxide, ion exchange resins, active carbon, active aluminium oxide, molecular sieves, alkaline oxide and/or porous supports containing lamellar double hydroxide modified or not and silica gel, or any mixture thereof to trap silicon and/or metals and/or phosphorous and/or halogenates trap, and/or water; c) performing a selective hydrogenation step at a temperature ranging from 25 to 225°C, preferably 200°C, a LHSV ranging from 1 to 10 h-1, a pressure ranging from 5 to 90 barg so that the effluent obtained at the exit of said selective hydrogenation step has preferably a diene value of at most 2.0 gl2/100 g even preferably at most 0.5 gl2/100 g as measured according to UOP 326; d) contacting the stream obtained at the step c), being preferably diluted with a second diluent, with a cracking catalyst being a 10 MR and/or 12 MR molecular sieve at a temperature ranging from 450°C to 650°C, a total pressure ranging from 0.5 to 10 barg and/or with an hydrogen partial pressure ranging from 0 to 7.5 barg to crack the olefins and/or paraffins of said pyrolysis plastic oil into olefins having 2 to 4 carbon atoms; e) separating from the effluents obtained at the step d) a first stream containing olefins and saturated hydrocarbons having at most 3 carbon atoms, and a second stream containing hydrocarbons having 4 or more carbon atoms; f) recovering from said first stream the ethylene and propylene. a) Providing a hydrocarbon stream containing at least 10 wt % of pyrolysis plastic oil preferably 25 wt %, even more preferably 50 wt %, even more preferably 75 wt %, the other part of said hydrocarbon stream being a first diluent or alternatively providing a hydrocarbon stream containing only pyrolysis plastic oil; b) Optionally putting in contact the effluent obtained at the step a) with silica gel, clays, alkaline or alkaline earth metal oxide, iron oxide, ion exchange resins, active carbon, active aluminium oxide, molecular sieves, alkaline oxide and/or porous supports containing lamellar double hydroxide modified or not and silica gel, or any mixture thereof to trap silicon and/or metals and/or phosphorous and/or halogenates trap, and/or water; c) performing a selective hydrogenation step at a temperature ranging from 25 to 225°C, preferably 200°C, a LHSV ranging from 1 to 10 h-1, a pressure ranging from 5 to 90 barg so that the effluent obtained at the exit of said selective hydrogenation step has preferably a diene value of at most 2.0 gl2/100 g even preferably at most 0.5 gl2/100 g as measured according to UOP 326; d) contacting the stream obtained at the step c), being preferably diluted with a second diluent, with a cracking catalyst being a 10 MR and/or 12 MR molecular sieve at a temperature ranging from 450°C to 650°C, a total pressure ranging from 0.5 to 10 barg and/or with an hydrogen partial pressure ranging from 0 to 7.5 barg to crack the olefins and/or paraffins of said pyrolysis plastic oil into olefins having 2 to 4 carbon atoms; e) separating from the effluents obtained at the step d) a first stream containing olefins and saturated hydrocarbons having at most 3 carbon atoms, and a second stream containing hydrocarbons having 4 or more carbon atoms; f) recovering from said first stream the ethylene and propylene. <EOS>