Abstract. A new process, named as Nano-powder Infiltration and Transient Eutectoid (NITE) process, has been developed and unidirectional SiC/SiC composites were prepared, and the effects of densification conditions on the microstructural evolution and mechanical properties were investigated. Carbon coated fibers were used as reinforcement and SiC nano-powders were used for matrix formation with certain amount of sintering aids. Density of the composites was improved with the increment of either temperature or pressure. Simultaneously, the interaction between fibers and matrix became strong. Highest tensile strength was obtained at 1780 C under 20 MPa in this work. Many advantages of the NITE process were suggested as, promising mechanical properties, moderate to high thermal conductivity, very low gas permeability and low production cost.