AIM:To observe the changes of ocular higher-order aberrations and corneal aspherical coefficient Q value and high aberration under different pupil diameter after conventional LASIK surgery using laser machine with small scanning spot 2mm active eye tracking system.METHODS: Thirty-three patients 60 eyes with myopia were received conventional LASIK surgery. The preoperative and postoperative 3 months records of total order aberrations, third order cornea, the fourth-order spherical aberration and corneal aspheric surface coefficient Q value in pupil diameter of 5mm and 6mm were examined and statistically analyzed. RESULTS: After LASIK surgery, 5mm and 6mm pupil diameters,higher order aberrations were increased significantly, especially in the fourth-order spherical aberration. There was significant increase in horizon coma than the vertical coma. Compared with under 5mm diameter higher order aberrations, those under 6mm were significantly increased before and after surgery. Corneal aspheric coefficient Q value significantly changed to the positive direction and there was significant difference after LASIK sugery.CONCLUSION: After conventional LASIK surgery with myopia, higher-order aberrations are increased significantly, especially in the fourth-order spherical aberration. After surgery, there is significant increase in the higher-order aberrations under 6mm pupil diameter than under 5mm pupil diameter. Corneal surface aspherical coefficient Q value is changed from negative to positive and there is significantly statistical difference.