Objective To examine which baseline predictive factors for axial length (AL) elongation over 2 years in children wearing orthokeratology lenses and single-vision (SV) spectacles. Methods This was a prospective non-randomized study. Eighty-two and eighty-four myopia patients (only took the right eye data) wore full correction SV spectacles and orthokeratology lenses, respectively. Gender, age, AL at baseline and 2 years after, and other parameters were collected. Univariate analysis was used to estimate the relationship between change in AL and baseline date of two groups. Results Two years later, 70 and 73 subjects finished follow-up in SV group and orthokeratology group, respectively. After univariate analysis, AL elongation was associated with the following factors in orthokeratology group. Change in AL was 0.34±0.29 mm and 0.21±0.31 mm for male and female, respectively (t=0.69, P<0.05). The regression coefficient between age (?茁=-0.066, P<0.01), age of myopia onset (?茁=-0.073, P<0.05), baseline myopia (?茁=0.052, P<0.05), myopia progression 2 years before baseline (?茁=-0.043, P<0.05), pupil diameter (?茁=-0.04, P<0.05), baseline AL (?茁=-0.06, P<0.05). AL elongation was associated with the following factors in SV group. The regression coefficient between age (?茁=-0.073, P<0.01), corneal astigmatism (?茁=0.05, P<0.05), baseline AL (?茁=-0.07, P<0.05). The regression coefficients of two groups between age, age of myopia onset, myopia progression 2 years before baseline, baseline myopia, corneal astigmatism, pupil diameter and AL were statistically significant after covariance analysis(P<0.05). Conclusion Orthokeratology was a successful treatment option in controlling AL elongation compared to SV spectale in children of female, younger age, had earlier onset of myopia, had greater corneal astigmatism and pupil diameter, had quicker rate of myopia progression before baseline, had higher myopia at baseline.