Abstract: A constructing method of a genomic scar model comprises: (1) collecting known BRCAness positive samples and known BRCAness negative samples to form a training set; (2) analyzing copy number variation (CNV) in the training set to determine types and corresponding quantities of CNV; (3) determining BRCAness positive events and BRCAness negative events; (4) training to obtain weights of different types of the CNV determined in the step 2 through a machine learning method according to the BRCAness positive events and the BRCAness negative events in the training set, and then totalizing the weights of the different types of the CNV to obtain the genomic scar model for calculating genomic scar score (GSS).