Objective  To observe the therapeutic effects of riboflavin-ultraviolet A（UVA） corneal collagen cross-linking （CXL） performed with a transepithelial method for progressive keratoconus. Methods  This was a prospective case series study. Thirty-six patients （54 eyes） with progressive keratoconus who underwent transepithelial corneal collagen cross-linking surgery were reviewed. The procedure was performed under topical anesthesia using a transepithelial corneal collagen cross-linking instrument （SOFT， Italy）. riboflavin （0.25%） was imported into the cornea for 10 minutes （current 1.0 mA）. The irradiation was performed for 9 minutes using a solid-state UVA illuminator at 370 nm and an irradiance of 10 mW/cm2. The average follow-up time was 14.1±2.3 months. Corneal epithelium healing was observed 1 day after surgery. There were no complications such as corneal ulcer， corneal dissolution， corneal epithelium mist opacity （haze） or severe pain. Uncorrected visual acuity （UCVA）； best corrected visual acuity （BCVA）； intraocular pressure； corneal curvature； corneal thickness； corneal topography； endothelial cell count； corneal biomechanical properties and in vivo confocal microscopy were evaluated at baseline and at 1， 3， 6， 12 months postoperatively. Data were analyzed using a paired samples t test. Results  The day after surgery， the corneal epithelium had opaque spots due to edema but the condition improved by the second day. Postoperative 12 months， UCVA and BCVA increased from 4.27±0.23 to 4.41±0.20 （t=3.962， P<0.01） and from 4.69±0.23 to 4.82±0.14 （t=3.507， P<0.01）， respectively. Interim analysis of treated eyes showed a flattening of the steepest simulated keratometry value （K-max） and astigmatism by an average of 1.25±0.68 diopters （t=9.351， P<0.01） and 0.30±0.21 diopters （t=7.227， P<0.01）. The deformation amplitude decreased from 1.21±0.11 mm to 1.16±0.12 mm（t=4.131， P<0.01）. Intraocular pressure， endothelial cell count and central corneal thickness did not change significantly. Conclusion  Transepithelial cornea