Halbach array is a new type of permanent magnet array. Its special permanent magnet arrangement structure can not only increase the air gap magnetic flux but also weaken the magnetic flux density of the rotor yoke, thus increasing the energy density while reducing the size and cost of the motor. For the Halbach array, when the rotor volume is constant, the volume of the permanent magnet used by the cubic permanent magnet is smaller than that of the sector-shaped permanent magnet. Therefore, the impact of special-shaped permanent magnets on the energy capture efficiency of the Halbach array can be explored. This paper compares the magnetic field distribution of three common special-shaped permanent magnets, rectangular, trapezoidal, and sector-shaped, under the same rotor volume, using the same volume of special-shaped permanent magnets and using the same volume of the rotor under two different operating conditions and energy efficiency. Simulations and experiments show that the energy capture effect of the Halbach array composed of sector-shaped permanent magnets is the best whether using permanent magnets of the same volume or rotors of the same volume.