This paper describes an adaptive self-guided loop filter for video coding. The filter acts as a loop filter to reduce the artifacts caused by quantization. The proposed filter is applied on the reconstruction samples of a Transform Unit (TU). The unfiltered input block is regarded as a guidance for self-guided edge-preserving smooth filtering. The filtering strength for each sample inside the input block is decided according to the TU size, corresponding QP, and statistical information generated from a designed filtering window adaptively. The proposed filter could be performed as a prediction-loop-filter in which the filtered samples can be referenced by intra prediction. Alternatively, the proposed filter can be moved to the post-loop-filter stage that after the deblocking filter for a low decoding dependency. The proposed method has been implemented and tested according to the common test conditions in Versatile Video Coding (VVC) test model version 11.0 (VTM 11.0). The post-loop-filter version can achieve 0.46% and 0.41% BD-rate reduction in All Intra and Random-Access configurations respectively.