Abstract: This paper presents the scheme, function and technical specifications of THz Vector Network Analyzers Spread Spectrum System. And we take steps to improve the performance of system, including multilevel amplification and frequency multiplication, low-order harmonic mixing, intermediary frequency (IF) receiver. Considerable dynamic range and other characteristics are obtained with these approaches. At the end of this paper, we describe the data sheet and technical specifications of THz Vector Network Analyzers Spread Spectrum System. and verify feasibility of the project studied in this paper．