(57) A method for forming a paper or paperboard web from a fibrous material in the wire section of a paper making machine or equivalent machine comprising a bottom wire loop (2;102) with the main portion of its top run being horizontal or substantially horizontal, and a top wire loop (10;110) working in conjunction with the bottom wire loop; wherein in the method fibre slurry coming out of the headbox (1;101) of the paper making machine is fed to the first part (2a; 102a) of the top run of said bottom wire loop (2;102), which forms the first dewatering zone after which the partly formed fibre layer is led to the second dewatering zone, in the area of which said top wire loop (10;110) moves to cover said partly formed fibre layer in such a way that water removal from the fibre layer continues it least in two stages in the area of said second dewaterlng zone, whereupon the top wire loop (10;110) is separated from the nearly formed web (W) that is led to follow the run of the bottom wire loop (2;102) forward to the next processing stages of the web (W), wherein the method is characterized in that in the single-wired dewatering zone (2a;102a), after the initial water removal is carried out through the bottom wire (2;102), water removal through the bottom wire (2;102) is prevented by means of an element group (9; 109) operating in contact with the inner surface of the horizontal top run of the bottom wires; that in said water-removal pre­vention area water is removed from the web (W) through the top wire in the first stage or stages of the double-­wired second dewatering zone, which stages comprise a relatively long, planar wire table extending from the headbox to the forming roll (6 in Fig. 1), or from the headbox to the last supporting element (109 in Fig. 2); and that after the first dewatering stage or stages of the double-wired zone water is removed in a curved double-­wired dewatering zone (b) (Fig. 1) or zones (R_o, C) (Fig. 2), after which the web (W) is led to follow the bottom wire (2;102).