A terahertz spectrum test device and system includes a femtosecond fiber laser configured to generate a pump light and a probe light. The pump light excites a terahertz transmitter to generate terahertz waves which are transmitted to a sample suspension device to irradiate a suspended to-be-tested sample, and the probe light is directly transmitted to a terahertz detector. The terahertz detector receives the terahertz waves transmitted from the sample suspension device, and then transmits the terahertz waves and the probe light together to a signal processing circuit to obtain a corresponding terahertz time-domain spectrum. By adoption of the terahertz spectrum test device and system, the to-be-tested sample need not be fixed with a clamp or other instruments, so that terahertz waves will not irradiate to the instrument used for fixing the to-be-tested sample during a terahertz spectrum test, which may otherwise affect the test result.