Sewing machine

The invention belongs to the technical field of sewing machines, and relates to a sewing machine. The sewing machine solves the problem that during formation of lock-stitch thread loops, an existing sewing machine is poor in stability. The sewing machine comprises a machine head, a main shaft and a needle rod, the main shaft is rotatably arranged on the machine head, a transmission mechanism capable of driving the needle rod to reciprocate in the vertical direction is arranged between the main shaft and the needle rod, and the lower end of the needle rod is provided with a machine needle; a needle plate used for the machine needle to penetrate through is arranged below the needle rod, in the process that the machine needle moves to the needle plate from the lowest displacement point of themachine needle, according to the stroke, the average speed of the machine needle is V1, in the process that the machine needle moves to the needle plate from the highest displacement point of the machine needle, according to