The classification of the mafic-ultramafic rocks is one of the basic problems in the research of the mafic-ultramafic rocks. The mafic-ultramafic rocks (exclude the kimberlite, lamprophyre and alkaline ultramafic rock, etc) can be divided into five types by the output tectonic background, rock suit and associated minerals. They are ophiolite, Yidun-type, Alaskan-type, layered intrusive type and peridotite-diorite type. The ophiolites represent ocean lithosphere mantle and its products of evolution. The Yidun-type represents the continental lithosphere mantle and its different products. The source rocks of the Alaskan-type are from island arc, epicontinental environment or with under arc characteristics of mantle. The layered intrusive type is from plate extensional tectonic setting. The peridotite-diorite type have similar tectonic background with Alaskan-type, but they are also found in intraplate environment. Ophiolite is one of the most concerned problems in academia, the author thinks that, the definition of ophiolite established in Penrose meeting of 1972 is still applicable and the concept of the Steinmann trinity is still effective. While the definition and classification made by Delik is not desirable. The author also thinks that the concept of Yidun-type is appropriate and useful. The ophiolite and Yidun-type have many similarities, but they have different meanings. The differences between them do not rely on rock suit or geochemistry, but rely on field output position and properties and structure of associated wall rocks. Different mafic-ultramafic rocks have different tectonic settings, and the associated deposit types and geotectonic significance are different. No matter in the field and laboratory study, paying attention to the differences between them is very important both in theoretical research and prospecting research.