The invention discloses a U bolt of an automobile transmission. The U bolt comprises a U bolt main body, wherein a ceramic heat shield is arranged inside the U bolt main body; a carbon steel alloy layer is arranged inside the ceramic heat shield; a stainless steel layer is arranged inside the carbon steel alloy layer; an aluminium core is arranged inside the stainless steel layer; a bolt body saddle is arranged at the bottom of the U bolt main body; a left bolt is arranged at one side of the U bolt main body; a left screw thread connector is arranged at the top of the left bolt; a left screw thread is arranged at the top of the left screw thread connector; a left bolt top is arranged at the top of the left screw thread; a left alloy nut is arranged at the side of the left screw thread; a metallic gasket is arranged at the top of the U bolt main body. The U bolt of the automobile transmission has good quality, is convenient to use and convenient and fast to install and dismantle, is low in casting cost and has an extensive application prospect.