Plant to produce a panel of multilayer MDF wood fiber obtained dry and consisting of at least three layers of wood fiber, of which at least one internal core layer and two external layers (11, 13) disposed adjacent to said internal core layer on opposite sides with respect to each other, said plant comprising: - two independent lines (15, 16) to feed wood fiber configured to respectively supply a first flow comprising wood fiber and a second flow comprising wood fiber, of which a first wood fiber feed line configured to supply the first flow comprising virgin wood fiber and a second wood fiber feed line configured to supply the second flow comprising recycled wood fiber or fiber obtained from a combination of recycled and virgin wood; - a station to form a multilayer assembly of aerated wood fiber, said forming station comprising in sequence in a direction of work: i) first depositing means able to deposit a first aerated layer of wood fiber coming from said first flow in order to form a first external layer, ii) second depositing means able to deposit a second aerated layer of fiber coming from at least said second flow in order to form the internal core layer above the first external layer, iii) third depositing means able to deposit a third aerated layer of fiber coming from said first flow in order to form a second external layer above the internal core layer obtaining a multilayer assembly of aerated wood fiber; - hot-pressing means configured to hot-press said multilayer assembly in order to compact the wood fiber and obtain a desired thickness; - cutting means configured to cut to size the multilayer assembly thus pressed in order to obtain said panel, wherein said first wood fiber feed line comprises at least one fiber preparation module configured to transform the wood into wood fiber through defibration by means of thermo-mechanical pulping, and said second wood fiber feed line comprises at least one respective fiber preparation module configured to transform the recycled wood into recycled wood fiber through defibration by means of thermo-mechanical pulping; wherein said second wood fiber feed line comprises at least one station to clean said recycled wood upstream of said fiber preparation module. - two independent lines (15, 16) to feed wood fiber configured to respectively supply a first flow comprising wood fiber and a second flow comprising wood fiber, of which a first wood fiber feed line configured to supply the first flow comprising virgin wood fiber and a second wood fiber feed line configured to supply the second flow comprising recycled wood fiber or fiber obtained from a combination of recycled and virgin wood; - a station to form a multilayer assembly of aerated wood fiber, said forming station comprising in sequence in a direction of work: i) first depositing means able to deposit a first aerated layer of wood fiber coming from said first flow in order to form a first external layer, ii) second depositing means able to deposit a second aerated layer of fiber coming from at least said second flow in order to form the internal core layer above the first external layer, iii) third depositing means able to deposit a third aerated layer of fiber coming from said first flow in order to form a second external layer above the internal core layer obtaining a multilayer assembly of aerated wood fiber; - hot-pressing means configured to hot-press said multilayer assembly in order to compact the wood fiber and obtain a desired thickness; - cutting means configured to cut to size the multilayer assembly thus pressed in order to obtain said panel, wherein said first wood fiber feed line comprises at least one fiber preparation module configured to transform the wood into wood fiber through defibration by means of thermo-mechanical pulping, and said second wood fiber feed line comprises at least one respective fiber preparation module configured to transform the recycled wood into recycled wood fiber through defibration by means of thermo-mechanical pulping; wherein said second wood fiber feed line comprises at least one station to clean said recycled wood upstream of said fiber preparation module. wherein said first wood fiber feed line comprises at least one fiber preparation module configured to transform the wood into wood fiber through defibration by means of thermo-mechanical pulping, and said second wood fiber feed line comprises at least one respective fiber preparation module configured to transform the recycled wood into recycled wood fiber through defibration by means of thermo-mechanical pulping; wherein said second wood fiber feed line comprises at least one station to clean said recycled wood upstream of said fiber preparation module.