| In order to study the influence mechanism of drought change on crop yield, taking the Jinghuiqu Irrigation Distric(ID) as the case study, selected the Standard Precipitation Index (SPI) as the drought evaluating index, using the methods of Mann-Kendall trend test and maximum entropy spectrum analysis to analyze the variation characteristics of drought in ID and the change rule of the climatic yield of winter wheat under drought evolution. The research showed that: (1) The real winter wheat yield in the ID has been showed a significantly rising trend (Z=7.6482), while the climatic yield was presented not obvious downward trend (Z=-0.5686); (2) The general drought trend in the ID was significant (through significant test at 99% level), this trend was reached remarkable level in three seasons as spring, summer and autumn; (3) The drought has existed periodic fluctuation of 16 years, the variation period was 4 to 5 years; (4) The drought situation in before planting as July to September and after planting as October to November had a great influence on climatic yield of winter wheat, these were the key periods for influencing crop climatic yield; (5) Climatic yield of winter wheat was closely related to SPI3-9, it can be explained 46.21% of the yield change; (6) With the change of the drought periodic cycle, r the correlation efficient of SPI3-9 with the climatic yield of winter wheat was increased from 0.44 to 0.74, the impact of drought on climatic yields was showed an increasing trend. |