Zoom metalens doublets, featuring ultra-compactness, strong zoom capability and CMOS compatibility, exhibit unprecedented advantages over the traditional refractive zoom lens. However, the huge chromatic aberration narrows the working bandwidth, which limits their potential applications in broadband systems. Here, by globally optimizing the phase profiles in the visible, we designed and numerically demonstrated a Moire lens based zoom metalens doublet that can achromatically work in the band of 440-640 nm. Such a doublet can achieve a...