Abstract: Objective To analyze the effect of Q-factor guided LASIK on Q factor value of the corneal anterior and posterior surface. Methods Twenty-three patients(46 eyes),admitted to our hospital for LASIK from May 2009 to January 2011,were divided into observation group and control group according to their dominant visual acuity eyes.Their non-dominant visual acuity eye underwent LASIK with the target Q-factor value set at 0.6-1.0.The Q factor of the corneal anterior and posterior surface in all eyes,examined with Pentecam method,was analyzed. Results No significant difference was found in Q factor value of the anterior and posterior corneal surface between the two groups before operation.The Q20,Q25,and Q30 value of the anterior corneal surface was 0.14,0.14 and 0.06 respectively in observation group and 0.27,0.28 and 0.20 respectively in control group after operation(P<0.01).However,no significant difference was found in Q35 and Q40 factor value of the anterior corneal surface between the two group after operation(P>0.05). Conclusion The Q factor value is lower after Q-factor-guided LASIK than after common LASIK.Q-factor guided LASIK can reconstruct the corneal aspheric surface and improve the visual acuity of presbyopic subjects.