This M.Sc. thesis is based on the following paper Hirano Yasuyuki, Edward Poon and Hisa Tsutsui., A generalization of complete reducibility, Communications in Algebra, 40(6):1901–1910, 2012. Throughout this review of thesis, we assume that a ring R is associative with an identity but not necessarily commutative. We say that a R -module M is a semisimple module or completely reducible module, if every R -submodule of M is a direct summand of M . A ring is said to be (left) semisimple if it is semisimple as a left module over itself. Hirano et al have studied rings whose left modules of finite length are semisimple and proved some results on such a ring and also they showed when such a ring is a left V-ring. It is well-known that R is a semisimple ring if and only if every R -module is semisimple so it is clear that “rings whose left modules of finite length are semisimple” are a generalization of semisimple rings. The main goal of this thesis is characterization of rings that every left modules of finite length are semisimple. At first, we show that for a ring R , every left R -module of finite length is semisimple if and only if every left R -module of length two is semisimple. We shall observe that if R is a left V-ring, then every left R -module of finite length is semisimple. In general, converse of last statement is not correct. We show that in commutative Noetherian rings, A ring R is called left semi-artinian if every nonzero left R -module has a nonzero socle. We show that if R is a left semi-artinian ring, then R is a left V-ring if and only if every left R -module of finite length is semisimple. We will give an example of a left semi-artinian von Neumann regular ring which has a module of finite length that is not semisimple. And also, we prove that if R is a module-finite algebra over a commutative ring, then R is a right and left V-ring if and only if R is a left max ring and every left R -module of finite length is semisimple.