The invention discloses a
library construction and sequencing method of
small RNA (Ribonucleic Acid). The construction method comprises the following steps: (1) connecting a
small RNA segment with a 3' connector of a CG
library; (2) connecting a product of step (1) with a 5' connector of the CG
library; (3) carrying out reverse transcription on a product of step (2) to form cDNA (
complementary Deoxyribonucleic Acid); (4) carrying out PCR (
Polymerase Chain Reaction) amplification on the cDNA; purifying and recycling a PCR amplification product; (5) carrying out single-chain separation on the purified and recycled PCR amplification product and cyclizing single-chain
DNA; (6) carrying out
enzyme digestion on a cyclized product and recycling to obtain a
small RNA CG library. According to the construction method disclosed by the invention, a novel CG library construction scheme is provided for the small
RNA so that whole-
genome level small
RNA sequencing based on CG sequencing is realized and a foundation is laid for novel small
RNA molecule digging,
cancer target gene predication and identification, difference expression and analysis between samples, small RNA clustering,
expression pattern analysis and the like and scientific evidence is also provided for
cancer early diagnosis and targeting treatment and detection.