Simple RNA library building method

The invention provides a simple RNA library building method which is characterized by comprising the following steps: (1) extracting RNA in a sample, adding a reverse transcription primer and an rRNA reverse transcription hindering probe, and fragmenting; (2) carrying out RNA reverse transcription to obtain DNA/RNA hybrid double strands; (3) linker connection: connecting a blunt-end double-chain DNA linker with adenylation modification to the 3'end of the DNA/RNA hybrid chain cDNA by using a T4 DNA ligase mutant K159L; and (4) library amplification and recovery. According to the simple RNA library building method, the principle that DNA ligase mutants K159L can be efficiently connected with DNA/RNA hybrid chains is utilized, only five steps of RNA fragmentation, reverse transcription, linker connection, library amplification and magnetic bead recovery are needed, the RNA library building process is greatly simplified, and consumed time is greatly shortened. In combination with a technology for rapidly removin