A method for screening bad data columns in a data storage medium comprising a plurality of data columns includes: labeling or recording a plurality of bad data columns as a bad data column group, wherein the bad data columns are selected from the data columns in the data storage medium, each of the bad data column groups labels or records a position and a number of the bad data columns; determining whether the total number of the bad data columns is greater than a total number of the bad data column groups; and if yes, labeling or recording any two bad data columns of the bad data columns spaced apart by P data columns as one of the bad data column groups, wherein P is a positive integer.