The invention discloses a flat knitting machine, and relates to the technical field of knitting machines. The flat knitting machine comprises needle beds, a driving mechanism and a traction mechanism; multiple insertion pieces which are arranged side by side at intervals are arranged on each needle bed, tooth mouth pieces are arranged under the front ends of the insertion pieces, a knitting needle is arranged between every two adjacent insertion pieces, and sinkers are arranged over the tooth mouth pieces; the driving mechanism drives the knitting needles to do reciprocating motion to achieve knitting, pressing rods are arranged at the front ends of the sinkers, the sinkers are movably arranged on the insertion pieces, the traction mechanism drives the sinkers to move forwards when the knitting needles conduct clearing, and the sinkers move forwards to in place and then rotate towards the tooth mouth pieces to enable the pressing rods to press loops. According to the flat knitting machine, the head of each pressing rod on the corresponding sinker can be driven by the traction mechanism to cross the symmetry center line of the two needle beds and can completely stretch into the space formed between every two adjacent tooth mouth pieces after the sinker rotates in place. Accordingly, no matter how the loops are lapped on the tooth mouth pieces in a floating mode, the heads of the pressing rods can stably and reliably press the loops to achieve the purpose of assisting the knitting needles in achieving clearing successfully.