Crop-livestock systems are critical for global agricultural sustainability. Here we show for the first time a new crop-livestock system: farming Muscovy ducks in maize fields (FD). To test whether FD is a practicable crop-livestock system, we conducted a 3-year field experiment to explore the growth and weight performance of Muscovy ducks in FD and to compare the FD with conventional maize planting (CMP) and raising ducks indoors (RDI) regarding crop growth and yield, weed biomass and density, feed conversion ratio, and economic benefits. We found that Muscovy ducks could adapt and thrive in maize fields with grain supplementation. The average weight per duck in FD at the harvest stage of maize was 2.24–3.82 kg, which met the local market standard and was higher than in RDI with a lower feed conversion ratio. When compared to CMP, FD did not significantly reduce the maize production in terms of yield or biomass, although the ducks fed on or damaged an average of four maize leaves. Importantly, FD significantly reduced the weed biomass and density. In addition, the net present value (NPV) of FD was $ 6690.47 per ha or $ 10.993 per duck, which was three times and 22.8% greater than those of CMP and RDI, respectively. These results indicated that FD, as a new crop-livestock system on dry land at the field scale, can promote sustainable agricultural production and act as a potential crop-livestock system due to the large global maize area.