Provided are an RNA library construction method and a specialized kit thereof. The method for preparing an RNA library includes the following steps: extracting RNA and performing fragmentation; adding a tail to 3' end; ligating an adaptor to 5' end and hybridizing with a DNA probe mixture; the DNA probe mixture is composed of several DNA probes that are reverse complementary to an RNA that is expected to be removed; removing RNA from the hybrid and removing DNA; performing reverse transcription and PCR amplification to obtain a library solution. The present invention combines poly A tailing and 5'end ligation. The RNA content in the system can be quickly increased by polyA tailing, thereby avoiding subsequent purification losses.