Terahertz is an emerging technology developed rapidly in the field of information science. The interaction mechanism between terahertz and material needs further exploration. Solid samples pretreatment is needed before terahertz measurement. In this paper, soil samples were selected for studying tablet-making process for terahertz time-domain spectroscopy measurement. Problems during tablet-making process were analyzed and the process was then optimized. Sample weight(130 mg, 180 mg, 220 mg, 280 mg, 330 mg, 400 mg) and the tablet-making pressure(every 0.5 t between 0.5-5 t, 1 t=1 000 kg) were selected as variables for studying the most suitable parameters for tablet-making for terahertz spectrum measurement. As a research, sample weight at 220 mg/ tablet and tablet-making pressure at 2.5 t were determined as the most suitable parameters. This research provides effective data for Terahertz measurement of soil samples using tablet-making method, and also provides a scientific reference for tablet-making method of other solid sample and THz measurement.