This paper proposes a new virtual Halbach analytical method for improved Halbach permanent magnet (PM) slotless planar linear actuators, which have mixed neodymium iron baron (NdFeB) magnets and ferrite magnets to form a two-segment quasi-Halbach topology with different heights of main and auxiliary magnetic poles. The method has four steps, which are described in detail in the paper. One of the key steps is to visually regard the permanent magnet region magnetized only in the y direction as a Halbach array structure with a magnetization amplitude of 0 in the x direction that satisfies the Newman boundary condition. The investigation shows that the results of the new analytical method are in good agreement with the finite element method. Using this analytical method, the effect of improved Halbach permanent magnet slotless planar linear actuator with unequal height of the main and auxiliary magnetic poles on the magnetic field waveform is analyzed by means of a parametric research.