This talk will introduce the origin of cell-free DNA (cfDNA) of human and the features of cfDNA sequencing data in the beginning. There are mainly two clinical applications of the cfDNA sequencing analysis: liquid biopsy for cancer patient and prenatal diagnosis. The technical and commercial aspects of the two applications will be overviewed in general. Also related commercial projects will be introduced that I had conducted. Brief reviews on the recent trends in cfDNA analysis technologies are followed.