The invention relates to a thin type electrodynamic loudspeaker. The loudspeaker comprises a speaker frame, and a magnetic circuit structure, a positioning support chip and a voice cone which are installed in the speaker frame, wherein the speaker frame is provided with a wiring board. The loudspeaker is characterized in that the magnetic circuit structure comprises a U-shaped magnetic conducting yoke, a magnet, a magnetic pole core and a voice coil, wherein the U-shaped magnetic conducting yoke is arranged in the speaker frame, and the outer bottom surface of the U-shaped magnetic conducting yoke is tightly combined with the upper bottom surface of the speaker frame; the magnet and the magnetic pole core are installed in the U-shaped magnetic conducting yoke, the lower surface of the magnet is tightly combined with the inner surface at the bottom of the U-shaped magnetic conducting yoke, and the upper surface of the magnet is tightly combined with the magnetic pole core; the voice coil is wound around the magnet and the magnetic pole core, a space is reserved between the inner wall of the voice coil and the outer wall of the magnetic pole core, and a space is also reserved between the outer wall of the voice coil and the inner wall of the U-shaped magnetic conducting yoke. The invention has the advantages of artful structure, compactness and reasonableness, optimizes the thickness while not decreasing the magnetic flux and the BL value, and can not produce excessive heat energy, thereby ensuring the acoustic performance and the reliability of the loudspeaker.