The invention relates to a projection system. The projection system comprises: a projector for projecting a display pattern; a reflection device for reflecting, shaping and amplifying a pattern generated by the projector, wherein the reflection surface of the reflection device faces the direct projection lens of the projector; and a base, wherein the projector and the reflection device are mountedon the base. The projection system is good in imaging effect, is matched with an arc-shaped surface of a rear window of an automobile, free of edge blurring and free of pattern deformation, is smallin occupied space and free of occupied space for passengers in the automobile, good in image stability when the automobile runs, has a slowing-down function, and is long in service life. The present invention further relates to a vehicle projection system.