The invention discloses application of aloperine to the preparation of an autophagic level inhibitor and a radiotherapeutic sensitizer for a radiotherapeutically resistant lung-cancel cell. The aloperine is a natural compound of a plant origin; the radiotherapeutic sensibilization mechanism of the aloperine is mainly to change biomarkers Beclin1, LC3 and p62, preferably fluorescently visual LC3 (Ad-mRFP-GFP-LC3), which are related to the autophagic level of a cell. Through detecting those specific biomarkers, those specific biomarkers are used for evaluating the autophagic level inhibition and a radiotherapeutic sensitization effect of the aloperine on the radiotherapeutically resistant lung-cancel cell.