Guoyu or Guo Yu may refer to:
國語
Standard Chinese, a standardized variety of spoken Mandarin Chinese usually called Putonghua in mainland China Taiwanese Mandarin, the related standardized variety of Mandarin in Taiwan Guoyu (book), a classical history book of ancient China
People Guoyu (name) Cheng Rui (died 903), Tang dynasty warlord known as Guo Yu at one point