Adjoint equations of characteristic singular integral equations are solved by another method which is different from the method given in the classical literatures.The method is to introduce an assistant function and using the polynomial analysis.Their solutions and conditions for solvability are abtained
which is as the same as those in the classical literatures.However
the method used here is given up in the classical literatures for some difficulty.In addition
we can get the equivalence of the theory ofsolvablity of characteristic and its adjoint equation by using this method.