Terahertz radar cross section (RCS) measurement is one of the most important techniques in terahertz applications. By using terahertz sources, the RCS of the targets and scale-models at terahertz band can be obtained, through which RCS of the full size targets at microwave band can also be calculated. Based on the definition of RCS and general requirements in the experiment, the main results of the terahertz RCS measurements abroad are provided. Three kinds of measuring facilities and targets and some typical measuring results are also emphasized. In the end, the characteristics in work frequency, size and miniaturization of targets and something else related when using terahertz time-domain spectrums system of femtosecond laser pumped crystal, inverse synthetic aperture radar system of CO2 laser pumped terhertz laser and coherent detection system with signal synthesizer are analyzed respectively, too. It helps to provide reference for the development of terahertz RCS measurement technology in our country.