Stability of a linear system with parameter uncertainty can be transformed as some inequalities in the form: g(q) or =, all q in Q (A), here q is parameter uncertainty vector q=(q1, q2,..., qt) Q is uncertainty set. Function g(q) can be etabilised with the aid of some concretealgebric stability criterion. The main diffculty for checking problem (A) is the checking of satisfy inequalty (A) with all value of q in Q. This articlepresentedoneanalytic method to check the robust stability of linear system with parameter uncertainty. Using the Routh or Hurwitz stability criteria, the stability of the system is led to the form (A) and g(q) is supposed in the polynomic form. Using the linear overboud one can find anasymptoticunder minimal value of function g(q) in the Q set, so that the strictly satisfaction to the inequalty (1) can be checked.