Abstract: Almost all flowering crops were polyploids plants, which whole genome had exprienced at least a time duplication events at an ancient time. With sequencing technology developing, the knowledge about crop genome and genome evolution had been renewed. In this paper, we reviewed some achievements acquired in polyploidy evolution and discuss the relationship between whole genome duplication and biological evolution. Whole genome duplication could increase the allele number, heterogeneity and diversity in polyploidy species. Meanwhile, doubled genome also made polyploidy plants to have more plasticity adapting to environment changes. At last, we discussed the possible application of duplication event in crop improvement.