This paper presents a set of the let-off mechanism of carbon fiber multilayer diagonal loom, which can accomplish thirty layer fabric weaving. This mechanism can realize multi-layer positive warp let-off and negative warp tension control and can meet different fabric structure and different types of warp weaving requirements. According to the requirement of the multi-layer weaving and the characteristics of carbon fiber, 3 d virtual prototype model of carbon fiber multilayer diagonal loom is established by applying the 3 d design software Solidworks and using the mechanical analysis software ANSYS analyses the mechanical properties of the key parts in different working conditions. Virtual prototype design ensures the rationality and reliability of the design of the whole machine.