A method and apparatus for sharing information in a video decoding system are disclosed. The method derives reconstructed data for a picture from a bitstream, where the picture is partitioned into multiple slices. An information-sharing flag is parsed from the bitstream associated with a current reconstructed slice. If the information-sharing flag indicates information sharing, shared information is determined from a part of the bitstream not corresponding to the current reconstructed slice, and in-loop filtering process is applied to the current reconstructed slice according to the shared information. If the information-sharing flag indicates filter no information sharing, individual information is determined from a part of the bitstream corresponding to the current reconstructed slice, and in-loop filtering process is applied to the current reconstructed slice according to the individual information. A method for a corresponding encoder is also disclosed.