The present invention provides a method for constructing a high-throughput sequencing library, which comprises: fragmenting genomic DNA; end-repairing the DNA fragments; adding a base A to the 3′ end of the end-repaired DNA fragments; connecting the DNA fragments having cohesive end A with a methylated adapter; carrying out hybrid capture on the connection products by using specific probes to obtain object fragments; treating the object fragments with bisulfite, to convert non-methylated cytosines to uracils; PCR amplifying the converted object fragments; and separating and purifying the amplification products, wherein the amplification products constitute the high-throughput sequencing library. The present invention also provides a method and an apparatus for identifying methylation information in specified genome regions of a sample.