The present work is a comprehensive treatment of structure-property relation of in situ TiB whisker reinforced Ti6Al4V(TiBw/Ti64) matrix composites with a network microstructure. A range of TiBw/Ti64 composites with varying the networkdegree were successfully fabricated by reaction hot pressing, where TiB whiskers were in situ synthesized along the “grainboundaries” of as-received spherical titanium particles and subsequently formed into a unique network microstructure. Thenetwork degree can be controlled by changing the Ti64 particle size and the overall volume fraction of TiBw reinforcement. Theresults of mechanical testing indicate that the mechanical properties of TiBw/Ti64 composites with a network microstructureare controllable and foreseeable by controlling the network degree. The strength and stiffness increase but the ductility decreaseswith increasing the network degree.