Abstract: Thinned and interleaved array design entails careful compromise between array sparseness and subarray interleaving. A new method for interlacing uniform planar array based on iterative fast Fourier transformation (FFT) algorithm is proposed in this paper. In view of the 2D-FFT-link between the array excitation and array factor of uniform planar array, the spectrum energy distribution of the discrete array factor of uniform planar array is explored and element excitations of interleaved subarray is carefully selected in an interlaced manner, which ensures the pattern matching of the generated subarray. The peak side lobe level of the interleaved array is further reduced with the FFT algorithm. Theoretical analysis and experimental simulation shows that compared with the existing cyclic difference sets (CDS) method, the proposed algorithm can achieve favorable thinned and interleaved array design with more matched patterns and lower peak sidelobe levels.