For　studying　the　inversed-order　problem　of　the　analytic　hierarchy　process　(AHP)　commonly　used,　the　definition　of　a　functional　operator　and　five　essential　keep-order　requirements　are　presented.　Furthermore,　keep-order　characteristics　of　frequently　used　functional　operators　(weighted　operators　for　synthesizing　judgments)　is　researched.　It　is　proved　that　weighted　product　technique　is　one　that　meets　all　five　keep-order　requirements.　The　research　supplies　references　for　the　selection　of　functional　operators　in　synthesizing　judgments.