Global climate change has raised many concerns especially on the food security. It becomes increasingly important to understand the underlying mechanisms and to find out strategies to adapt climate change. Climate data from 1954 to 2015 at one representative experimental station in the North China Plain, model simulation, and a 5-year field experiment from 2011 to 2015 worked together to detect effects of climate change on maize yield and adaption methods. In the field experiment, two foliar fungicides “Cabrio” and “Opera” were sprayed at 9-leaf stage of maize to delay leaf senescence under four different plant densities (67,500, 75,000, 82,500, and 90,000 plant ha−1) and two nitrogen levels (120 and 180 N kg ha−1). In the past six decades, growing degree days (GDD) significantly increased at a rate of 4.4 °C yr−1, solar radiation significantly decreased at a rate of 12.93 MJ m-2 yr−1, and annual precipitation slightly decreased at the experimental site. The climate change tended to significantly reduce maize yield in the cropping system winter wheat – summer maize in the North China Plain. The reduced growing period (particularly reproductive growing period) by the warming climate could explain the reduced maize yield. Foliar fungicides greatly delayed leaf senescence especially at high plant densities and low nitrogen levels. On average, leaf area index was 2.7 vs. 1.9 between treatments of spraying fungicides and spraying water at harvest. Dry biomass was significantly increased by fungicides especially in the late growing period. Together with increased leaf productivity, 10-day delayed harvest could offset the adverse effects of climate change on maize yield in the past six decades in the North China Plain. Varieties and crop management that can increase reproductive growing period as well as enhance leaf productivity of maize (particularly in the early grain filling period) are likely to produce more yield and adapt to the progressive climate change.