Data collection was done on flood/drought-induced loss of agricultural products and also crop fields from 29 provinces(municipality) in period of 1961-2010. Change properties were analyzed using trend test method such as Mann-Kendall trend test in this study to investigate spatio-temporal distribution of flood/ drought hazards and related impacts on agricultural productivity over China. The results indicated that: 1) Flood hazards are significant increasing trends in middle, mid-west and northwest parts of China. Evident increase of drought hazards, however, is observed in northwest, northeast parts of China and also in the Yunnan Province. In China except north China and northeast China, flood hazards have enhancing impacts and no evident negative impacts from drought hazards can be identified; 2) Abrupt changes of flood-affected and flood-damaged crop areas in the northeast, north and middle China are found mainly during 1980s and during 1990s in the south and southwest China. The abrupt changes of drought-affected crop areas however are detected mainly in 1984 and those of drought-damaged crop areas in south and north China are mainly in 1977 and 1984 in the middle and east China; 3) Spatio-temporal alterations of flood/drought hazards result in evident increase of hazard-induced loss and loss rate. Conspicuous impacts of flood/drought hazard on agricultural productivity can be detected in west and north China; 4) Increased seasonal precipitation amount and also the intensifying precipitation extremes give rise to increasing intensity and frequency of flood/drought hazards in northwest, southwest and middle China. Decrease of seasonal precipitation amount results in higher frequency of droughts in northeast and north China. This study is of great significance in planning and management of agricultural activities under the influences of climate change across China.