Abstract: Aiming at resolving the problem of fault detection mistake under the noise environment in aerial vehicle dynamic process，a new-style observer is constructed，which is based on the method of LMI．This observer is applied as residual generator，which uses[H∞]norm to describe the robustness of the residual against external disturbance in fault detecting.The actuator fault can be detected accurately by restraining the noise effect and the solution of the robust observer estate matrices is deduced．A failure aerial vehicle’s longitudinal model is applied in the simulation.The experimental results show that the design of this paper can check out the fault promptly and accurately and suppress noise effectively．