Method for producing panels in thermoplastic material consisting of a three-dimensional central strip element and two flat strip covering elements (P2, P3) firmly fastened to the central strip element, comprising the following steps: - continuously extrusion of a first strip by means of a first extrusion assembly which feeds a first cylinder shaped to produce said three-dimensional central strip element; - continuous extrusion of a second strip by means of a second extrusion assembly which feeds a second cylinder to produce one of said flat strip covering elements, said second flat strip element being made to adhere to the second cylinder; - continuous extrusion of a third strip by means of a third extrusion assembly which feeds a third cylinder to produce the other of said flat strip covering elements, said third flat strip covering element being made to adhere to the third cylinder; characterised in that said three-dimensional central strip element leaving the first cylinder is coupled to said flat strip element obtained by means of the second extrusion assembly in a gap between the first cylinder and the second cylinder as a result of the intrinsic heat of the extruded material and of the pressure exerted in the gap between the two cylinders (13, 23), in that the composite structure obtained by coupling said three-dimensional central strip element and said flat strip covering element is in turn coupled to the other flat strip covering element obtained by means of the third extrusion assembly in a gap between the second cylinder and the third cylinder as a result of the intrinsic heat of the extruded material and of the pressure exerted in the gap between the two cylinders (23, 33), and in that said first, second and third strips (P1, P2, P3) are made to adhere to the respective cylinders (13, 23, 33) by creating vacuum. - continuously extrusion of a first strip by means of a first extrusion assembly which feeds a first cylinder shaped to produce said three-dimensional central strip element; - continuous extrusion of a second strip by means of a second extrusion assembly which feeds a second cylinder to produce one of said flat strip covering elements, said second flat strip element being made to adhere to the second cylinder; - continuous extrusion of a third strip by means of a third extrusion assembly which feeds a third cylinder to produce the other of said flat strip covering elements, said third flat strip covering element being made to adhere to the third cylinder; characterised in that said three-dimensional central strip element leaving the first cylinder is coupled to said flat strip element obtained by means of the second extrusion assembly in a gap between the first cylinder and the second cylinder as a result of the intrinsic heat of the extruded material and of the pressure exerted in the gap between the two cylinders (13, 23), in that the composite structure obtained by coupling said three-dimensional central strip element and said flat strip covering element is in turn coupled to the other flat strip covering element obtained by means of the third extrusion assembly in a gap between the second cylinder and the third cylinder as a result of the intrinsic heat of the extruded material and of the pressure exerted in the gap between the two cylinders (23, 33), and in that said first, second and third strips (P1, P2, P3) are made to adhere to the respective cylinders (13, 23, 33) by creating vacuum.