We report defects study in 4H-SiC bulk crystals grown by sublimation method on micropipe filled seed crystals oriented (0001) on-axis. The seed crystals of 1~3 inch in diameter were prepared from the large 4H-SiC bulk crystals. Before the sublimation growth, micropipes of the seed crystals were filled with epilayers grown by micropipe filling technique of CVD method. We confirmed about 95% of micropipes perfectly disappeared in the grown crystal. The mechanism of the micropipe extinction was also defined by defect analysis.