Myopia has become a noteworthy issue due to the increasing use of our eyes. We propose a continuous power variation vision-training device based on Alvarez lenses with the power ranging from $10\mathrm{D}$ to $+2\mathrm{D}$. First, we introduce the principle of Alvarez lenses and the evaluation method of dioptric power and astigmatism. Then, we optimize the optical system described by Zernike polynomials. Finally, we analyze the distributions of dioptric power and astigmatism with the overall surface analysis and fields of view (FOVs) analysis. The results show that the optical performance of an optimized system can meet the requirement within a 40° FOV.