Abstract:The possible slipping and twinning modes in hop metals are summarized. The slipping plane includes (0000) hasal. (1100)prismatic plane and c-type. c+a-type Pyramidal plane. {1012}. {1121}and {112 2}are the primary twinning modes. {1011} {1124}and {1123}type twins are possible to appear in Ti and Zr.The relationship between slipping mode and the tasting temperature in Ti and Zr is discussed. The slipping planes arranged in order of ease of operation are prismatic.pyramidal and hasal planes.