We propose a deblocking algorithm using multi-scale edge representation of images. All block-based image/video coding methods suffer the annoying blocking artifacts at low bit rate. Blockings are considered as tiny edges occur at the borders of coding blocks in the directions of horizontal or vertical. These directional and magnitude specialties characterize blockings from other common edges in nature images, and can be reasonably used in the designing of deblocking algorithms. We decompose an image using dyadic wavelet transform and then find the local extrema of wavelet coefficients, which are corresponding to edge points. The extrema caused by blockings are eliminated using some predefined criteria. The de-blocked image can be reconstructed from those filtered extrema with a Projection Onto Convex Sets (POCS) method. Experimental results show that the proposed method can generate fairly well deblocking results under various bit rate conditions.