Based on the excimer laser cornea correction mathematical model and the clinical wave-front aberration data,the influence of treatment decentration on wave-front aberration in conventional laser refractive surgery is studied. The result reveals that treatment decentration may induce the distinct increase of coma. The induced coma is nearly proportional to the treatment decentration and the corrected refraction. But other Zernike coefficients except for coma from third- to fifth-order aberrations approximatively maintain constant with the increase of treatment decentration. The increase of higher-order aberrations after refractive surgery may be attributed to the treatment decentration,the effect of oblique incidence of laser spot and the effect of biological response of the cornea.