Second-order computational homogenisation[1] provides an efficient framework for capturing size effects and strain gradient behaviour in heterogeneous materials, yet its application to 3D woven composites has largely been restricted to shell-based macroscopic descriptions with limited representation of fully three-dimensional strain-gradient effects[2]. In this work, a kinematically consistent second-order homogenisation framework is developed for 3D woven composites using solid elements at the macroscale, enabling the direct treatment of thick structures and fully three dimensional deformation modes. The macroscale displacement field is formulated to incorporate both the deformation gradient and its spatial gradients. Corresponding microscale boundary value problems are formulated on heterogeneous 3D woven representative volume elements using periodic boundary conditions and additional integral constraints to enforce the Hill-Mandel condition for higher-order continua[3]. The framework is implemented within an FE2 formulation using user-defined macro solid elements and iterative constraint enforcement, allowing consistent extraction of homogenised higher-order stress measures and tangent operators. The formulation accommodates 3D architectures and enables solid-to-solid homogenisation, allowing strain-gradient effects to be captured consistently in all three spatial directions beyond the kinematic limitations inherent to 2D and shell-based elements. The proposed formulation is verified through a series of numerical simulations under bending and transverse shear dominated loading, and the results are compared with high-fidelity models, as well as first-order homogenisation to highlight the importance of higher-order effects for thick and strongly heterogeneous structures such as 3D weaves. The proposed approach provides a general and extensible framework for multiscale analysis of thick composite structures where strain-gradients effects are significant in all three spatial directions.