Provided is a method of mass-producing high-purity nucleotides including providing a sequencing substrate having a clonal library of oligonucleotides on a solid support, sequencing the clonal library, obtaining measured location data of the solid support on the sequencing substrate, mapping pixel data of a signal generated from the solid support given as a result of the sequencing with the measured location data, extracting the solid support having a desired base sequence from the sequencing substrate using the mapping result, and amplifying an oligonucleotide on the extracted solid support to replicate on a large scale.