Sewing machine

The utility model discloses a sewing machine which comprises a front reflection type detection piece, a rear reflection type detection piece and a controller, and the front reflection type detection piece comprises a front transmitting end and a front receiving end which are integrally arranged; the rear reflection type detection piece comprises a rear transmitting end and a rear receiving end which are integrally arranged; the controller controls the presser foot assembly to be lifted when the front end of the sewing material passes through the front reflection type detection piece accordingto a pulse signal fed back by the front receiving end; the controller controls the thread trimming assembly to trim threads according to pulse signals fed back by the rear receiving end when the frontend or the rear end of the sewing material leaves the rear reflection type detection piece. The controller further controls the thread trimming assembly not to act according to the pulse signals fedback by the rear receiving