Many researchers found that stress environment induced the formation of polyploidy plant. Simultaneously, it might be the stress that acted as a key factor to select polyploidy plants to survive in that rigid environment. The size of cells and organs in polyploidy plants were always larger, but not of the size of the whole plant. Polyploidy plants had increased resistance in some major stress environments such as low temperature, high temperature, drought, salinity and pathogenic stress. The elevated resistance to stress was achieved due to changing the cell dimension and structure, changing the membrane system, enhancing the osmotic substances, elevating the activity of antioxidative system, altering the gene expressing and epigenetic changes. However, there were also researchers showed that the stress resistance of polyploidy plants was shrunk down. We could not illustrate the mechanism of stress resistance of polyploidy plants unless do more detailed studies. This article presents a review on the formation and characteristics of polyploidy plants and its response and regulation mechanisms under stress conditions.