A system for page detection using light attenuators is applied in a book to detect an opened page of the book. The book has N pages and each page has a page detection area in which at most M light attenuators are installed in each page detection area. A light source passes through the at most M light attenuators for attenuating intensity of the light source. M light sensing devices are installed in an area of the book that corresponds to the page detection area. The M light sensing devices are used to detect attenuated intensities of the light source. A controller is connected to the M light sensing devices for detecting the opened page based on a ratio of the intensities of the light source detected by the M light sensing devices on each page.