The present disclosure provides a stellarator magnet based on cubic permanent magnet blocks and an arrangement optimization method thereof. For the characteristic that a three-dimensional magnet coil of a stellarator is complex in structure, the present disclosure provides the stellarator magnet based on the cubic permanent magnet blocks with uniform magnetization, same magnetization and same size; the magnetization directions of the cubic permanent magnet blocks are defined in a limited number of fixed alternative directions; the magnetic field configuration of the stellarator is generated by dipole magnetic fields provided by the permanent magnet blocks and planar coils, so that the device complexity of the stellarator is reduced, and the difficulty and cost of the machining and installation of the magnet are reduced. The shape of the permanent magnet blocks can be replaced by other regular shapes, and the permanent magnet is still formed by the permanent magnet blocks with same shape, same size, uniform magnetization and same magnetization. For the magnet, the present disclosure provides a magnet arrangement optimization method of ‘local compensation’ and related optimization strategies of ‘threshold truncation,’ ‘global fine tuning,’ etc., for meeting different optimization requirements on accuracy of the magnetic fields, usage qualities of magnets, etc., and a magnetic field meeting designing requirements can be obtained.