The micro-structural fabric and topology play a key role in macroscopic responses of granular materials. Generally, the contact network is formed by connecting centers of interactive particles, which could be divided into strong and weak contact subsets. Different topological, geometrical and mechanical characteristics could be found for the two parts of network and the threshold is somehow artificial. Based on true triaxial DEM simulation results, this paper focuses on the fabric anisotropies and the connectivity characteristics of strong contact networks distinguished by different contact force thresholds, moreover the roles of partides with different coordination numbers in the strong networks are identified. The strong contact network characterizes the main features of the macro stress tensor and the proper threshold for discriminating strong and weak contact networks falls in a range. Partides connected by 2 contacts are important in forming the strong contact network and reflecting the main features of force anisotropy. (C) 2020 Elsevier B.V. All rights reserved.