A flat knitting machine structure with an adjustable gap between two knock-over bits , comprising: two needle beds , disposed at interval respectively comprising a plurality of needles , wherein each of the plurality of needles defines a needle extending line and comprises a butt which is positioned on the needle extending line ; and two cam systems , respectively disposed to face one of the needle beds (11 or 12), wherein each of the cam systems comprises a needle cam to provide the butts being placed and guide each of the plurality of needles to make a knitting stroke towards the gap , the two needle beds respectively comprise a plurality of knock-over bits disposed to correspond to each of the plurality of needles , the plurality of knock-over bits facing each other to define a gap , wherein a distance of the gap is equal to a space between two knock-over bits facing each other, wherein the flat knitting machine structure is characterized in that each of the plurality of knock-over bits comprises a control butt disposed at a same side as each of the butts , an extending section provided with the control butt , a bending section connected with the extending section and a loop hanging section connected with the bending section as well as paralleled to a front edge of one of the needles , and wherein each of the control butts is respectively positioned on one of the needle extending lines in which one of the plurality of needles is correspondingly disposed; and the two cam systems respectively comprise a knock-over bit cam providing the control butts being placed, wherein the knock-over bit cam is controlled to define a displacement stroke for driving the plurality of knock-over bits to change the size of the gap . two needle beds , disposed at interval respectively comprising a plurality of needles , wherein each of the plurality of needles defines a needle extending line and comprises a butt which is positioned on the needle extending line ; and two cam systems , respectively disposed to face one of the needle beds (11 or 12), wherein each of the cam systems comprises a needle cam to provide the butts being placed and guide each of the plurality of needles to make a knitting stroke towards the gap , the two needle beds respectively comprise a plurality of knock-over bits disposed to correspond to each of the plurality of needles , the plurality of knock-over bits facing each other to define a gap , wherein a distance of the gap is equal to a space between two knock-over bits facing each other, wherein the flat knitting machine structure is characterized in that each of the plurality of knock-over bits comprises a control butt disposed at a same side as each of the butts , an extending section provided with the control butt , a bending section connected with the extending section and a loop hanging section connected with the bending section as well as paralleled to a front edge of one of the needles , and wherein each of the control butts is respectively positioned on one of the needle extending lines in which one of the plurality of needles is correspondingly disposed; and the two cam systems respectively comprise a knock-over bit cam providing the control butts being placed, wherein the knock-over bit cam is controlled to define a displacement stroke for driving the plurality of knock-over bits to change the size of the gap . <EOS>