Objective To evaluate the corneal biomechanical changes after femtosecond laser-assisted in situ kerato-mileusis(FS-LASIK)combined with accelerated corneal cross-linking(FS-LASIK Xtra)for the correction of high myopia u-sing Corvis ST.Methods In this prospective case-control study,185 patients(185 eyes)who underwent surgical correc-tion of high myopia in the Affiliated Eye Hospital of Shandong University of Chinese Medicine from July 2020 to July 2022 were selected,including 93 patients receiving FS-LASIK Xtra in the FS-LASIK Xtra group and 92 patients receiving FS-LASIK in the FS-LASIK group.All patients had their right eyes included in the study.During the 6-month follow-up,the uncorrect-ed visual acuity,spherical equivalent(SE),mean corneal curvature,thinnest corneal thickness,corneal biomechanical pa-rameters[deformation amplitude ratio at 2 mm(DAR 2 mm),integrated radius(IR),stiffness parameter at the first appla-nation(SP-A1),stress-strain index(SSI)],and changes in corneal biomechanical parameters before and after surgery(difference between 6 months after surgery and before surgery,namely ΔDAR 2 mm,ΔIR,ΔSP-A1,and ΔSSI)were recor-ded.Independent sample t test and Mann-Whitney U test were used to compare the data between groups.Results Three months after surgery,the SE in the FS-LASIK group and the FS-LASIK Xtra group was(-0.21±0.31)D and(-0.04±0.36)D,respectively,and the difference was statistically significant(t=3.49,P=0.001).Six months after surgery,the SE in the FS-LASIK group and the FS-LASIK Xtra group was(-0.33±0.31)D and(-0.14±0.37)D,respectively,and the difference was statistically significant(t=4.00,P＜0.001).There was no significant difference in efficacy index and safety index between the FS-LASIK group and the FS-LASIK Xtra group at 6 months after operation(both P＞0.05).There were no significant differences in DAR 2 mm,IR,SP-A1,SSI and other biomechanical parameters between the two groups before surgery(all P＞0.05).At 6 months postoperatively,ΔIR in the FS-LASIK group and the FS-LASIK Xtra group was 3.03±0.78 and 2.67±0.80,respectively;ΔSP-A1 was-35.93±12.04 and-30.43±12.44,respectively;and ΔSSI was-0.09±0.10 and-0.03±0.06,respectively.The differences between the two groups were all statistically significant(all P＜0.05).Conclusion FS-LASIK Xtra for correction of high myopia improves the stability of postoperative visual acuity and SE with good safety and efficacy,but reduces the stability of comeal biomechanical parameters compared with before surgery;still,it is better than conventional FS-LASIK,and the long-term effect needs to be further assessed.