Magnetic circuit structure and loudspeaker

The utility model relates to a magnetic circuit structure and a loudspeaker. The magnetic circuit structure includes a U-shaped iron, a main magnet, a washer and an auxiliary magnet. The main magnet, the washer and the auxiliary magnet are sequentially laminated in the U-shaped iron and form a circular magnetic circuit gap with the inner wall of the U-shaped iron. The washer includes a first magnetic area, and a second magnetic area. The first magnetic area is cylindrical and the lower end face of the first magnetic area matches the main magnet. The second magnetic area is truncated-cone-shaped and the upper end face of the second magnetic area matches the auxiliary magnet. The loudspeaker includes the magnetic circuit structure, a voice coil, a basin stand, a drum paper and a damper. The arranged first magnetic area and second magnetic area of the magnetic circuit structure enable the washer and the U-shaped iron to effectively obtain the energy of a magnetic field and the magnetomotive forces of the first magnetic area and the second magnetic area are distributed more symmetrically and when the magnetic circuit structure is applied to the loudspeaker, the voice coil obtains identical magnetomotive forces during moving in the magnetic circuit gap so that low-frequency distortion of the loudspeaker is reduced and the performance and quality of the loudspeaker are improved.