The safety storage life of seeds is the time taken for seed viability reduced from the original value to the regeneration standard. The safety storage life of germplasm resources under low-temperature or ambient storage is rarely studied. To address this question, the viability monitoring data of rice and wheat seeds that being stored at the National Genebank, mid-term genebank and ambient conditions were analyzed. Viability of 3500 rice accessions and 3279 wheat accessions in the National Genebank and 801 accessions in Guangxi mid-term genebank were monitored by germination test after being stored for 20 to 22 years or 17 to 19 years respectively. Results showed that over 99% rice seeds and 96% wheat seeds could be safely conserved for more than 20 years in the National Genebank. In the mid-term genebank, the safety storage life of rice was shorter than that of the National Genebank, but still over 17 years. The germination percentages of rice and wheat seeds stored under ambient condition in different climatic regions suggested that the viability of seeds kept in the low temperature region was higher than that in the warmer ones, and the safety storage life of seeds with optimum moisture contents was longer than 14 years. The length of the safety storage life was related to not only the storage conditions but also the initial quality and the variety types of the seeds.