Orthokeratology is becoming popular for the treatment of myopia children. Many studies have shown that orthokeratology is effective in temporarily reducing refractive error, and is also helpful for controlling myopia progression. However, the mechanism for its slowing myopia progression and rebound effect after the treatment have not been clearly studied. In addition, the effect of orthokeratology among Chinese children has not been evaluated with randomized controlled trial.This study is to assess the effect of orthokeratology versus spectacles on myopia progression in school-aged Chinese children during two years.