Terahertz time-domain spectroscopy (THz-TDS) is one of the main research platforms for terahertz (THz) science and technology. However, a traditional system is not only bulky but also has some limitations in detecting micro and liquid samples because of the large THz beam spot dimensions and the strong THz-wave absorption by water. We have developed a THz-TDS measurement chip by directly fabricating THz transmission lines and photoconductive antenna electrodes on a low-temperature GaAs epitaxial wafer. This chip integrates THz-waves generation device, detection device, and the transmission line in the size of 1  mm  ×  20  μm and uses the between the THz evanescent field sample interaction near the transmission line to obtain the spectral information from the trace or liquid samples. Using a self-built measurement beam path, we tested the chip with 1550-nm femtosecond laser and obtained THz spectroscopy in the 0.1 to 0.7 THz range, thereby verifying the feasibility of the chip.