We have developed an NGS-based deep bisulfite sequencing protocol for the DNA methylation analysis of genomes. This approach allows the rapid and efficient construction of NGS-ready libraries with a large number of PCR products that have been individually amplified from bisulfite-converted DNA. This approach also employs a bioinformatics strategy to sort the raw sequence reads generated from NGS platforms and subsequently to derive DNA methylation levels for individual loci. The results demonstrated that this NGS-based deep bisulfite sequencing approach provide not only DNA methylation levels but also informative DNA methylation patterns that have not been seen through other existing methods.•This protocol provides an efficient method generating NGS-ready libraries from individually amplified PCR products.•This protocol provides a bioinformatics strategy sorting NGS-derived raw sequence reads.•This protocol provides deep bisulfite sequencing results that can measure DNA methylation levels and patterns of individual loci.