This paper introduces the Concurrent Subsystem Robust Design Optimisation method, and studies the simple application of the method to the design of an aircraft. The Concurrent Subsystem Robust Design Optimisation method and other two different methods are adopted in computation; the robust result indicates that the Concurrent Subsystem Robust Design Optimisation method is better than the other two methods. There are three ameliorations in the new method, the first one is that uncertainty analysis is added under MDO circumstance. Secondly, it is allowed to use disperse variable in the system level. Thirdly, neural network response surface is applied to providing measurable information.