Yunnan Province has plenty of light resource in its southern subtropical zone where both hybrid rice and winter sown maize yield high.Besides,thermal condition is also very good with 6000 to 7500℃·d of ≥10℃ accumulative temperature for a whole year,smaller annual and greater diurnal temperature difference.Such climate as warm winter and cool summer can make maize be planted any time in a year,being typical of the southern subtropical climate zone for the crop.Not so high temperature in summer when sunshine is weak in some degree causes lower yield of the hybrid rice.Rainfall is distributed unevenly either in season or in space,though its annual total amount is proper,and within dry spring and winter seasons it is only 10% to 15% of the total,accordingly restricting growth of the winter sown maize and pre jointing rice.To develop water conservancy and irrigation therefore is the most important for achieving high and stable yields of rice and maize in this zone.