The Clarkson-Kruskal direct method was proposed by Clarkson and Kruskal,which is an algebraic method for solving nonlinear partial differential equations.The advantage of this method is that it does not involve group theory operations and complex initial value problems.It can give new similarity solutions of the nonlinear evolution equations which could not be obtained by the classical Lie group method and the nonclassical Lie group method.By using the Clarkson-Kruskal method and corresponding rules,the symmetry reduction and the similarity transformation of the Drinfeld-Sokolov-Satsuma-Hirota equation were obtained.It is verified that the results by the Clarkson-Kruskal method can be transformed into those by the classical Lie group method.