The invention relates to a high-power density permanent magnet motor belonging to the field of motors. The invention solves the problems of low efficiency and thrust density, large thrust fluctuation and high vibration and noises of the traditional double-edge ironless straight line permanent magnet synchronous motor, which are caused by low air gap magnetic density and poor sine degree of air gap magnetic density wave forms. An air gap is positioned between a primary pole and a secondary pole of a straight line motor; main permanent magnets and isolated magnets are sequentially arranged on the inner wall of a yoke plate at intervals; the inner sides of the main permanent magnets are provided with assembling magnets which have same widths along a motion direction; the inner sides of the isolated magnets are provided with auxiliary permanent magnets which have same widths along the motion direction; the outer side surfaces of m auxiliary permanent magnets and m assembling magnets are positioned on a same plane; the main permanent magnets are parallelly magnetized in magnetizing directions perpendicular to the motion directions of active cells, and every two adjacent main permanent magnets are in reverse magnetizing directions; the auxiliary permanent magnets are parallelly magnetized in the magnetizing directions parallel to the motion directions of the active cells, and every two adjacent auxiliary permanent magnets are in reverse magnetizing directions.