A projection system capable of projection alignment includes a projector, a shaped projection screen, an image sensor, and a processing unit. The projector is configured to project a series of alignment content to the shaped projection screen. The image sensor is configured to capture a series of projected alignment content. The processing unit is electronically coupled to the image sensor and configured to receive the series of captured alignment content and determine at least part of general boundary of the shaped projection screen based on the series of captured alignment content.