This contribution is corresponding to CE2 test 2.2.1.5 and proposes changes on filtering process of deblocking filter on large block boundary. To improve visual quality by removing blocking artifact on large and smooth block boundary, it is proposed to selectively apply an additional longer tap strong filter. The proposed strong filtering process is different according to block edge direction. The number of filtered pixels are reduced in horizontal edge than vertical in order to reduce line memory for longer tap filter. The test results show that the proposed method achieves 0.03%, -0.02% and 0.10% BDBR for AI, RA, LDP compared to VTM1.0 and 0.03%, 0.03% and 0.07% BDBR for AI, RA, LDP compared to BMS, respectively.