Recent years, the motion deblurring algorithm based on deep learning has been widely concerned, while single defocus image deblurring is rarely studied. In order to specifically solve the defocus blur problem of single image, this paper proposed a defocus deblurring algorithm based on deep recurrent neural network. Firstly, the algorithm used two cascaded residual networks to estimate the defocus map and image deblurring, respectively. After that, to ensure that the depth features of defocus map and clear images could better propagate across stages and interact within stages, the algorithm introduced LSTM ( long short-term memory) as a recurrent layer in the residual network. Finally, the whole residual network underwent several iterations and reused the network parameters during the iterative stages. To train the network, this paper produced a synthetic defocus blur image dataset, where each defocus blurred image contained a corresponding clear image and defocus map. The experimental results show that, compared with existing defocus deblurring methods, the proposed algorithm has significant advantages in both the subjective and objective image quality evaluation, and can produce sharper edges and clear details in the restoration results. On the real defocus blur dual-pixel image dataset DPD, the proposed algorithm improves the peak signal-to-noise ratio ( PSNR) and structural similarity( SSIM ) by 0. 77 dB and 5. 6%, respectively, compared with DPDNet-Single. Therefore, the proposed method can effectively deal with defocus blur in real scenes. [ABSTRACT FROM AUTHOR]