In the extended range improved design of certain type of rocket launcher, in order to solve the problem of severe ablation and low stiffness with the GFRP barrel, present a design scheme of barrel with GFRP and stainless steel, analysis the factors affecting the stiffness of barrel and theoretical calculation were obtained, verified the feasibility of the scheme through ANSYS and ballistic launcher firing test. The results show: barrel with GFRP and stainless steel get good qualities of those materials, can meet the requirements of small weight, rigidity, resistance to erosion and corrosion resistance, the improvement design requirement of target shooting accuracy and range of the ballistic missile are both achieved, provide theoretical basis and reference to engineering application of improved design of barrel in rocket launcher.