Disclosed herein are a method and apparatus for normalizing the size of content in a multi-projection theater and a computer-readable recording medium. The method may include receiving theater parameters stored in a database, computing the scale factor of an image project on a main screen based on the received theater parameters, controlling the image projected on the main screen by incorporating the computed scale factor into the image, and controlling an image projected on a sub-screen so that the height or width of at least any one of images of sub-screens having a different pixel size or ratio from the controlled image of the main screen is identical with a height or width of the controlled image of the main screen.