The present invention a cylinder liner which controls gap formation at the interface between the cylinder liner and a cylinder block main body for accepting the cylinder liner therein, and serves to acquire closely contacting state and enhanced bonding strength between the cylinder liner and the cylinder block main body, and to provide a cylinder block, and further to provide a process for the preparation of the cylinder liner.A plurality of circumferential grooves 15 extending in the circumferential direction is formed from a first circumferential groove 16 having a shape of “J” of the alphabet in sectional view and extending in a circumferential direction formed on an outer surface 12 of an cast iron cylinder liner 10, and a second circumferential groove 18 having a shape of “J” of the alphabet in sectional view and linking to the first circumferential groove 16. In enclosing the cylinder liner 10 in a cylinder block main body 30 by casting, the movement of a molten aluminum alloy is depressed by the circumferential grooves 15 and therefore a residual stress generated on the solidification and shrinkage is equally dispersed whereby cracking of the cylinder block body 3 can be prevented and close contact and bonding strength at interface between the cylinder liner 10 and the cylinder block main body 30 are ensured.