Objective To investigate the efficacy and safety of using stereotactic radiotherapy (SRT) technique for conducting re-therapy after thoracic tumor radiotherapy.Methods Thirty-eight patientswith SRT after receiving thoracic conventional radiotherapy (RT) in our hospital from July 2012 to November 2014 were selected.The treatment target area included the lung local primary lesion,recurrent lesions and lung metastasis tumor.Results Median dose of previous RT was 48 Gy (30-56 Gy).Median biologically equivalent effective dose (alpha/beta=10.0,BED10) of receiving SRT was 62 Gy (39-72 Gy).Median follow up time was 12.30 months;1-,2-year local progression-free survival (LPFS) was 76.32％ and 63.16 ％ respectively.Median recurrence-free (RFS) and overall survival (OS) were 13.20 months and 21.00 months respectively.Grade 2 and 3 pulmonary toxicity was 15.79 ％ and 7.89 ％ respectively.Other grade 2-4 toxicities adverse reactions included chest pain (15.79 ％),fatigue (18.42 ％) and skin lesion(2.63％).No grade 5 toxic injury occurred.Conclusion SRT can be safely and effectively used in the patients previously receiving thoracic RT.