The beating is alleged to have happened after the student posted a photograph of him and another student on social media wearing their school uniforms, the Samoa Observer reports.
Principal Leoloa Tuuu Mautofiga, of Palalaua College on Upolu, has not commented on the matter.
The student, Brian Vaela'a, told the newspaper he believed the photo was not damaging to the school's reputation nor were there any rules prohibiting the posting of photos in uniforms.
His mother said a nurse at the district hospital filed a report with police after treating her son's injuries.