Recently, a significant growth in the development and applications of textile composites has been seen in many engineering fields.Due to the complex microstructures, the behaviours of textile composites are difficult to be accurately predicted.In the context of structural modelling, it is impossible to capture all the details of microstructures inside textile composites structures.Hence,engineers usually use homogenized properties for structural modelling, which come from a typical pattern of textile composites in a subscale of the structure.In this paper, a novel multiscale modelling approach based on Mechanics of Structure Genome（MSG） is proposed to analyse textile composites structures.MSG was recently discovered as a unified approach for multiscale constitutive modelling of heterogeneous structures and materials [1].Compared with traditional approaches [2-4], MSG greatly reduces the computational time and maintains accuracy as three-dimensional（3 D） finite element analysis（FEA）.Since no ad hoc assumptions are made in the theory, MSG provides a rigorous approach to analyse all kinds of textile composites.Figure 1 shows the framework for MSG-based multiscale modelling.The properties of individual constituent（e.g.fibres and matrix） are treated as inputs for the following microscale model.At microscale, the effective properties of yarns are obtained from fibres and matrix.Then, the constitutive relation of different structures（e.g.beam, plate/shell and solid） can be computed based on effective yarn properties and matrix properties, which are later used for structural analysis.After structural analysis, the local stress/strain fields can be obtained by MSG dehomogenization analysis.In this paper, two different models are used to compute the effective properties of yarns at microscale.The first model is 2D square packed SG [5] as shown in Figure 2（a）, which are often used in many micromechanics approaches.The effective yarn properties are obtained from this model using MSG periodic boundary conditions（PBCs） in x-, y-and z-directions.Another model is proposed considering elliptical yarn cross section shape as shown in Figure 2（b）, which removes the periodicity in the in-plane direction using MSG aperiodic boundary conditions（aPBCs）.Once the properties of yarns are obtained from microscale homogenization analysis, the constitutive relation of the textile composites can be computed from MSG mesoscale modelling.In this paper, a plain woven composites is first analysed using MSG solid model（Fig.3）, and the results are compared with the corresponding 3D RVE analysis using FEM.A 3D FEA model made by 3-layer plain woven composites with all the yarn and matrix details are analysed using Abaqus 6.13.The same model is analysed by using MSG beam model and plate model respectively.The displacements along the longitudinal direction（ x1） of the 3D FEA model, MSG beam model and MSG plate model are shown in Figure 4.The local stress σ11 distribution within beam SG