Electromagnetic waves in the terahertz band has significant application scenarios such as security screening, material analysis, biomedical, communications and military applications. In recent years, atom-based terahertz electric field measurement, characterized by high sensitivity, ultra-broad bandwidth, high resolution and the ability to be directly traceable to fundamental physical constants (the Planck constant), has widely attracted attention. The measurement capability across microwave and terahertz bands enables Rydberg atoms to partially overcome the limitations of traditional terahertz measurement methods. Various research teams have successively reported the application of electromagnetically induced transparency (EIT) spectroscopy based on Rydberg atoms in microwave electric field measurement, such as field strength power, phase, frequency, angle of arrival, polarization direction, among others. Currently, there is no relevant research validating the terahertz broadband measurement capability of thermal Rydberg atoms. Therefore, it is necessary to design an atom-based terahertz field measurement system to demonstrate that using thermal Rydberg atoms as "antennas" for electric field measurement can cover an extremely wide working frequency range.The THz electric field measurement system operates at room temperature, using a glass cell filled with Cs atomic vapor as the platform to achieve THz field strength measurement. A probe laser, resonant with the ground-state transition and stabilized via saturated absorption spectroscopy, excites atoms to the first excited state. A coupling laser excites atoms to Rydberg state (principal quantum number n>10). Quantum coherence effects create an EIT spectral signal (Fig.1(b)), which splits into an Autler-Townes (AT) signal under a resonant THz field, with the splitting width proportional to the electric field strength. The frequency coupling with the Rydberg transition calculated by Alkali Rydberg Calculator (ARC), between 0.1 THz and 1.5 THz (Fig.2). The probe laser passes through the vapor cell and is detected by a photodetector. The coupling laser is generated by a tunable semiconductor laser (507-513 nm). The 0.1-0.5 THz generation system employs signal sources and Frequency multiplier with waves directed into the vapor cell via a horn antenna.By theoretical calculation, it is found that there are large number of frequency points between 0.1 THz and 1.5 THz, coupling with the Rydberg transition with large electric dipole moment, that is to say, it is proved that quasi-continuous frequency measurement in a wide frequency band can be realized by using Rydberg atom. By using the frequency separation between the fine structure levels nD_5/2-nD_3/2, the horizontal axis of the measured AT splitting spectrum can be converted into frequency. When the PZT voltage of tunable semiconductor laser, which is proportional to the frequency of laser, changes by 1 V during the scanning cycle, the ratio of the time interval $ {\Delta }{t} $ between the peaks and the frequency separation $ {\Delta }{f} $ between the peaks is approximately 5 486.53 MHz/s (Tab.1). In the experiment, the AT splitting width under different terahertz field strengths was measured. THz electric field detection at multiple frequencies in 0.1- 0.5 THz is realized by using the same atom vapor cell (Fig.6), and the measured AT splitting interval increases with the field strength acting on atoms (Fig.5).A terahertz field measurement system based on atoms is designed and build, transforming the terahertz field strength measurement into an optical frequency measurement. This scheme offers advantages such as broadband and direct traceability to fundamental physical constants. It’s proved that the same vapor cell can be used to measure terahertz fields in the frequency range from 0.1 THz to 1.5 THz, and the terahertz field strength measurement is ability to measure terahertz field strength within the 0.1 THz to 0.5 THz range. Rydberg atoms possess high-sensitivity electric field measurement and broadband frequency analysis capabilities, which lays a foundation for Rydberg atom to measure weak THz signal in THz radar, safety detection, biological research and other aspects as well as THz metrology.