With one step sintering technique the in-situ synthesis high content TiB₂/SiC composites were synthed using SiC, TiO₂ and B₄C as the main raw material. The effect of TiB₂ content on volume resistivity, microstructure and mechanical properties of TiB₂/SiC composites were studied by the Vivtorinox hardness tester, electronic universal testing machine, volt ohmmeter, optical microscope and SEM. The results show that with the increase of TiB₂ content, the average particle porosity decreased firstly and then increased, the flexural strength and fracture toughness were increased first and then decreased, the Vivtorinox hardness increased gradually, electrical resistivity decreased rapidly and then tended to be stable and TiB₂ particle size increased. After sintering at 1950 C, the content of 40 wt% TiB₂ has the best performance, the open porosity, flexural strength, fracture toughness and volume electrical resistivity were 0.56%, 412 MPa, 5.77 MPa m_1/2 and 2.6×10_-1 (Ω?cm).