A web-forming section of a paper or board machine has a first web-forming unit with a first fiber layer (W1) formed on a first wire (10); a second web-forming unit with a second fiber layer (W2) formed on a second wire (30); and a couch shoe (39) over a curved deck (40) of which the fiber layers (W1, W2) are guided for joining them together. The second fiber layer (W2) is brought to the couch shoe (39) at an angle (α) of less than 20°, advantageously less than 15° in relation to the approach direction of the first fiber layer (W1). The couch shoe (39) is provided with underpressure and the radius of curvature of its deck (40) is usually larger than the radius of curvature of a guide roll (38) preceding it. By the couch shoe, the fiber layers can be joined together wetter than usual.