Abstract: The space-time dynaraics of soil water of dry1and wheat are analysed under same natural conditions in three different annual rainfall conditions (wet year，normal year and dry year)by using regression isogram method，The results show that the soil water “peak”,“ridge”，“slope”and“saddle”formed by regression isogram had different characters under different annual rainfall conditions，and theye are also difference among the zones of wilt value and the isogram value．Then different soil water dynamics and wheat yields Were formed under different rainfall condition.