A mask plate and an evaporation system. The mask plate includes at least one mask strip. Folding structures are connected to two opposite sides of the at least one mask strip. At least one group of effective evaporation area and transition area located around the effective evaporation areas are arranged on the at least one mask strip. Each folding structure includes a foldable part and a support part connected to each other. The foldable part is connected to the support part and the mask strip. The foldable part and at least part of the support part are sequentially stacked on one side of the two opposite sides of the mask strip, and the foldable part covers at least part of the transition area close to the folding structure of the mask strip.