Objective To investigate the effects of cryoanalgesia for post-thoracotomy pain on the intercostal nerves. Methods Two hundred and eight patients suffering from thoracotomy were divided into three groups, according to different analgesia received respectively. Cryoanalgesia group （n = 80）： cryoanalgesia on the intercostal nerves, intercostals nerves was freezed at -55 ℃ for 90 seconds ; patient controlled analgesia by vein （PCA group, n= 80）： patient controlled analgesia was practiced intravenously, and control group （n = 48）： Dolantin given irregularly intra-muscularly and/or tramadol orally. Severity of pain was graded by visual analogue scale. Forced expiratory volume in one second（FEV1.0） was measured and pulmonary complication after operation was compared. Results There was a statistically significant improvement in postoperative pain scores and an improvement in respiratory function tests for patients in cryoanalgesia group（X2 = 74.93,15.04,P〈0. 05）. FEV1.0 in cryoanalgesia group was significantly higher than that in control group（1. 97±0.27L vs. 1. 39±0. 14 L,P〈0. 05）. Pulmonary complication in cryoanalgesia group after operation was lower than that in control group （6. 25% vs. 31. 25%, P〈0. 05 ）, Conclusion Cryoanalgesia on post-thoracotomy pain is very effective and may improve the respiratory function after operation.