AIM: To evaluate the predictability, stability, efficacy of laser in situ keratomileusis (LASIK) using varied size spot laser for the treatment of myopia and compound myopic astigmatism. And analyse risk factors in residual refrac-tion after LASIK. METHODS: A total of 768 samples (eyes) were enrolled in this retrospective study in our surgery center from Oct. 2008 to Oct. 2009. The inclusion criteria were spherical equivalent (SE) no more than -10.00D, follow-up periods more than one month and BCVA no less than 0.8. The samples were divided by surgery mode and power of SE. The uncorrected visual acuity (UCVA), residual refraction of one month, three months, six months, one a after surgery and the preoperative and postoperative data of regression samples were used for statistics. RESULTS: Ten samples lost the BCVA; 98.0% samples were within 0.50D of emmetropia and 99.2% of the samples were within 1.00D of conventional LASIK(conven-tional group), 97.4% and 99.3% of wavefront-guided LASIK(wavefront-guided group) respectively; the residual refraction was - 0.01±0.10D at one month, - 0.02±0.20D at three months, - 0.07±0.31D at six months, - 0.15±0.38D at one year postoperatively in conventional group and the residual refraction was -0.01±0.08D at one month, - 0.01±0.09D at three months, - 0.03±0.15D at six months, - 0.08±0.19D at one year postoperatively in conventional group. The change in visual acuity (posto-perative UCVA preoperative BCVA) was 0±0.05 and 0.01±0.04 of the two groups respec-tively. Analysis of the residual refractive error of the 23 samples of residual refraction: residual spherical (RS) was related to age and preoperative spherical, residual spherical = 1.355- 0.034 age + 0.142 preoperative spherical; residual cylinder was related to preoperative cylinder and preoperative center corneal thickness, residual cylinder =3.489+0.238 preoperative cylinder -0.007 preoperative center corneal thickness. CONCLUSION: Varied size spot LASIK is predictable, stable, and effective for the treatment of myopia and compound myopic astigmatism, wavefront-guided LASIK was better than conventional LASIK on the aspect of predictability and efficacy, both surgery modes have a good stability; age and preoperative spherical power were risk factors for residual spherical, preoperative cylinder and preoperative center corneal thickness were risk factors for residual cylinder.