In this paper the Fuehsian theory of linear ordinary differential equation is generalized to the asymptotic solutions for equation [t,m,(d/dt),m,+a,1,(t)t,m-1,(d/dt),m-1,+…+a,m,(t)]u=0. In complex plane the existence and uniqueness of asymptotic solution are proved. The existence and uniquaness of asymptotic solution in class CS° are also proved.