A wave-front reconstruction technique of cyclic radial shearing interferometry (CRSI) based on least-squares is proposed. First,it divides a single CRSI figure into four sub-figures and then obtains the phase difference distribution of the interferogram by least-squares iteration. By using the wave-front reconstruction algorithm of CRSI,the real wave-front can be obtained with the phase difference distribution. The simulations show that the accuracy is better than λ/50 (peak value,PV) and λ/300 (root mean square,RMS). The feasibility of this technique is experimentally verified. This technique overcomes the problems of spectrum shifting and low precision,which exist in traditional wave-front reconstruction of CRSI based on fast Fourier transformation(FFT). And it can be used to reconstruct wave-front with only one CRSI figure,and also can be used in dynamic measurement of beam wave-front.