A method and apparatus for deblocking of reconstructed video in a video coding system are disclosed. Embodiments according to the present invention determine boundary strength between two blocks without checking whether the block boundary is a coding unit (CU) boundary. In one embodiment according to the present invention, the method comprises determining whether any of the two blocks is Intra coded. If any of the two blocks is Intra coded, the boundary strength is assigned a first value. Otherwise, additional decision processing is performed to determine the boundary strength. In another embodiment, said determining the boundary strength for the block boundary comprises determining whether the block boundary is a TU boundary and whether any of the two blocks contains coefficients. In yet another embodiment, said determining the boundary strength for the block boundary comprises determining whether the two blocks have different reference pictures or different motion vectors.