A projection system and a projection method are provided. The projection system includes a first projector and a second projector. A first projection image projected by the first projector and a second projection image projected by the second projector are partially overlapped. A projection region edit menu is executed to display multiple adjustment points and multiple connecting lines on the first projection image. A position of a selected adjustment point among the multiple adjustment points and positions of two connecting lines connected to the selected adjustment point among the multiple adjustment points displayed on the first projection image are changed according to a first moving instruction to select a closed region formed by the multiple connecting lines in a non-overlap region of the first projection image. The projection method is adapted to the projection system that provides a blending projection effect of multiple projectors having an even brightness.