Thread changing mechanism of sewing machine

The utility model relates to a thread changing mechanism of a sewing machine, which aims at solving the technical problem that a bobbin containing less threads can fall off from a bobbin when the current sewing machine works, and comprises a sewing machine support, a sewing machine main body is arranged at the top end of the sewing machine support, and a thread changing device is arranged at the top end of the sewing machine main body. The yarn changing device comprises a rotating shaft, one end of the rotating shaft is provided with a fixing device, the fixing device comprises a circular plate, and one side of the circular plate is provided with a long shaft. By pulling the circular plate, the steering column installed on one side of the circular plate rotates around the axis of the sliding block, a bobbin is placed on the rotating shaft, and the bobbin is placed on the rotating shaft. Then the long shaft is rotated to enable the rotating shaft to be in lap joint with the limiting groove, the circular plate