Multiaxial Warp Knitted (MWK) fabrics play an important role in the field of industrial applications due to their desired mechanical properties. Since the beginning of 1990's, MWK fabrics have been widely used for structural composites to produce aerospace components, marine parts and automotive frames and become the preferred 3D textile composite preform. Although some reports can be found on the prroduction technology, general structure and properties of MWK fabrics as well as their composites, there is not so far any model dealing with the design of mechanical properties in terms of fabric structure parameters. This greatly restrains the application of this kind of fabrics. In this paper, a uniaxial tensile model is established, and a formula for calculating tensile modulus of the fabric in any direction is presented. With this model, the tensile properties of MWK fabrics can be designed to meet the particular requirements for composites applications.