AIM: To evaluate the effectiveness of Grand Seiko Ref/Keratometer WAM-5500 compared to Topcon KR800 autorefractor in detecting refractive error in large scale vision screening for Chinese school age children with the WHO criteria. METHODS: A total of 886 participants were enrolled with mean age of 9.49±1.88y from Tianjin, China. Spherical equivalent (SE) was obtained from un-cycloplegic autorefraction and cycloplegic autorefraction. Topcon KR 800 (Topcon) and Grand Seiko WAM-5500 (WAM) autorefractors were used. Bland-Altman Plot and regression were generated to compare their performance. The overall effectiveness of detecting early stage refractive error was analyzed with receiver operating characteristic (ROC) curves. RESULTS: The mean SE was -0.98±1.81 diopter (D) and the prevalence of myopia was 48.9% defined by WHO criteria according to the result of cycloplegic autorefraction. The mean SE of un-cycloplegic autorefraction with Topcon and WAM were -1.21±1.65 and -1.20±1.68 D respectively. There was a strong linear agreement between result obtained from WAM and cycloplegic autorefraction with an R2 of 0.8318. Bland-Altman plot indicated a moderate agreement of cylinder values between the two methods. The sensitivity and specificity for detecting hyperopia were 90.52% and 83.51%; for detecting myopia were 95.60% and 90.24%; for detecting astigmatism were 79.40% and 90.21%; for detecting high myopia were 98.16% and 98.91% respectively. CONCLUSION: These findings suggest that both Grand Seiko and Topcon autorefractor can be used in large-scale vision screening for detecting refractive error in Chinese population. Grand Seiko gives relatively better performance in detecting myopia, hyperopia, and high myopia for school age children.