The invention relates to miR-129 and an application of target genes of the miR-129 to detection of lung adenocarcinoma. A high-flux sequencing method is used for seeking genes being obvious in difference expression in the lung adenocarcinoma and tissues close to the lung adenocarcinoma. In combination of bioinformatics analysis and literature investigation and research, miR-129 and the target genes MFAP3L and RPH3A of the miR-129 are selected from the candidate miRNA and are subjected to RT-PCR verification and database verification. Results indicate that the miR-129 and the target genes thereof have good relevance to the lung adenocarcinoma. The invention provides new important target points for gene diagnosis and treatment of the lung adenocarcinoma for clinical treatment.