The invention discloses a miRNA marker.The miRNA marker is miRNA-1304 which can be used for judging whether squamous cell lung carcinoma is metastatic or not or pre-judging the metastasis risk of squamous cell lung carcinoma.It is proved through tests that by means of miRNA-1304, a squamous cell lung carcinoma metastasis sample and a non-metastasis sample can be effectively differentiated.Based on this, miRNA-1304 can be further used for preparing medicine for inhibiting or preventing metastasis of squamous cell lung carcinoma.By means of the miRNA marker, a new diagnosis method is provided for clinically diagnosing metastasis of squamous cell lung carcinoma on the molecular level, and meanwhile a new medicine target spot is provided for gene therapy of metastasis of squamous cell lung carcinoma.