Objective To study the measurement differences of central corneal thickness(CCT) in different degree of myopia by Sirius and ultrasound pachymetry(UP). Methods 225 myopic subjects(450 eyes)were recruited and divided into three groups according to the degree of refractive errors. The CCT were obtained from the eyes for each subjects using the Sirius and UP. Data were compared by using paired t-tests and the Pearson correlations. Bland- Altman analysis of all pairs were determined. Results The mean CCT in low myopic group obtained from Sirius and UP were (542.61±29.19)μm and(538.51±29.12)μm,respectively. The mean CCT in medium myopic group by Sirius and UP were(543.96±27.02)μm and(540.98±26.56)μm.The measured mean CCT in high myopic group were(547.25±22.53)μm and(542.19±21.64)μm by Sirius and UP. The mean CCT measurements between the two instruments were high correlated and statistically different(P<0.05) in the three groups respectively. In different myopia groups Sirius has good coincidence with UP in measuring CCT according to the Bland-Altman plot. Conclusion In vast majority of cases,Sirius can replace traditional UP in measuring CCT. But for the preopreative examination of the high myopia patients, we need to think twice about the difference between the two measurements.