This paper is concerned with the control problem of linear systems with part uncertain parameters under a bounded energy noise-the parameter robust control. The flight control of airplane with a precise model under an uncertain information condition of aerodynamic parameters, is a typical example. At first we simplify it into a scaled H_∞ control problem, and then deduce a solvability condition and give an explicit expression of the complete solution set for the parameter robust control problem by J-lossless factorization method.