The objective of this study is to make full use of natural resources,to analyze the yield potential of sum-mer maize in different regions in Henan province and to find the ways to bridge the gap between potential and actual crop yield .Based on daily meteorological observation data,yield data of summer maize in 96 counties in the target region from 1961 to 2010,a successive correcting model was used to calculate photo-thermo productivity (YT) and climate productiv-ity (YW) and clarify the yield gap between YT and DeltaYW,the yield gap between YT and actual productivity (DeltaYA),the spatial-temporal characteristics of two types of yield gap in the past 50 years .The results showed that YT increased from the north to the south and form the east to the west of the province,but it showed a diminishing trend during the past 50 years,with a decreasing rate of -696 .8kg·hm~(-2)·10a~(-1) .This is in particular obvious for most of the stations in north-ern and central areas and part of the stations in southern areas .DeltaYW decreased obviously,with a rate of -958 .7 kg·hm~(-2)·10a~(-1) .The actual yield of summer maize increased significantly, while DeltaYA decreased with a rate of -1 718 .0 kg·hm~(-2)·10a~(-1) .The yield gaps were over 24 000 kg·hm~(-2),in 71 .9% of stations,indicating a substantial yield potential .The precipitation is the key restricting factor on yield in the west of Henan province,suggesting the ne-cessity of irrigation .The shortage of heat resources at later stage is the influencing factor in the north,implying the im-portance of selecting early maturity varieties and improving agronomical practices in this area .In addition,expending irri-gation area,choosing suitable varieties and reasonable fertilization can be used to bridge the yield gaps in the east .