A grass-cutting head (10) comprising a spool (11) for winding at least one cutting line and a housing (12) for the cutting line, wherein said housing (12) comprises a first part (13) and a second part (14) coupled to each other so as to allow at least one reciprocal angular movement around the axis (X) of rotation of the grass-cutting head. The housing (12) presents at least one passage (31) towards the outside for the cutting line. On the spool (11) is defined at least one inserting portion (33) for inserting the cutting line so that to a rotation of the spool corresponds a winding or an unwinding of the line. Means (25, 26, 27, 28, 29) are furthermore present for winding the cutting line on the spool (11) and matching means (35, 36) for matching the angular position of the portion (33) of insertion on the spool (11) with said passage towards the outside (31) of the housing, suitable to facilitate the operations of inserting the cutting line in the spool (11). The matching means (35, 36) for matching the angular position comprise at least one reversible coupling between at least one abutment (35) associated as with one of said first (13) and second (14) part, and a corresponding counter-abutment (36) associated with the other of said first (13) and second (14) part.
