Heilongjiang province is now the largest rice producing area and commercial rice area in China, but there are many rivers, and heavy rain and rainstorm in summer make it more likely to cause waterlogging. In order to study the impact of flood disaster on rice yield in cold region, field submergence experiment was conducted in 2017 to analyze the differences in seed setting rate and yield caused by different submergence depth and duration of submergence in key growth period of rice in cold region. The results showed that: under submergence stress during these periods such as elongation-booting stage,Flowering stage and milk stage for Longjing 31, percentage of ripened grains and yield decreased to varying degrees. They obviously decreased with increasing submergence depth and time, for example, when submergence depth was from 2/3 to 3/3 plant height, and submergence time was from 3 to 7 days, yield loss was about from 31.1% to 65.2%. The analysis of variance showed that the seed-setting rate and yield of Longjing 31 and Longdao 18 under full submersion were extremely significant（P＜0.01）, which were lower than the flooding depth of 2/3 and 1/3 of the plant height, and the seed-setting rate（P＜0.01）, which lasted for 7 days, was significantly lower than the flooding depth of 3 days. Under the condition of deep submergence, the yield and seed setting rate of rice could be decreased by prolonged submergence stress. When the depth of field water reaches 25 cm and the duration of submersion exceeds 3 days, the seed setting rate and yield of rice will decrease,while when the depth of submersion is 25 ～ 50 cm or above and the duration of submersion exceeds 3 days, the seed setting rate and yield of rice will decrease significantly.