AIM:To discuss the reason for refractive regression after laser in situ keratomileusis (LASIK). METHODS:There were 152 cases (287 eyes), men 62 cases, women 90 cases, aged 17 to 50 years old. Preoperative LASIK refraction with all patients was - 6.00 ~ -15.00 D.According to refraction ,they were divided into A group of 142 eyes (- 6.00 ~-9.00D), B group of 101 eyes (-9.25~-12.00D) and C group of 44 eyes (-12.25~-15.00D).They were recorded with different gender, age, refraction, corneal thickness, corneal refractive power and corneal laser ablation zone diameter, and analyzed statistically after LASIK. The mean follow-up time was 1 year. RESULTS:A group:refractive regression rate of surgery eye was 3.1%, the average number of refraction was -1.01±0.56D, 1 year after surgery the average corneal bed thickness of normal surgery eye was 457.1±30.1μm, regressive surgery eye was 396.2±32.0μm, the intraoperative mean diameter of ablation zone for the normal surgery eye was 6.22±0.37mm, regressive surgery eye was 5.73±0.38mm, all of the differences were significant (P<0.05). B group:refractive regression rate of surgery eye was 10.2%, the average refraction was -1.69±0.81D,1 year after surgery the average corneal thickness of normal surgery eye was 443.1±32.9μm, regressive surgery eye was 303.4±29.0μm,the intraoperative mean diameter of ablation zone for the normal surgery eye was 6.02±0.16mm, regressive surgery eye was 5.66±0.21mm, all of the differences were significant (P<0.05). C group:refractive regression rate of surgery eye was 11.3%, the average refraction was -1.96±1.76D, 1 year after surgery the average corneal thickness of normal surgery eye was 439.1±30.1μm, regressive surgery eye was 279.0±28.0μm,the intraoperative mean diameter of ablation zone for the normal surgery eye was 5.87±0.21mm, regressive surgery eye was 5.51±0.15mm, all of the differences were significant (P<0.05). CONCLUSION:LASIK can treat myopia of - 6.00~ -15.00D effectively. Patients of high myopia with preoperative thin corneal thickness and patients with a small intraoperative laser ablation zone diameter are prone to postoperative refractive regression.