Su, X.L. Du, Y.-C. Huang, W.-H. Liang, Y.F. Niu, L. Tang, C.-X. Tian, Q.L. Wang, D. Yan, L.X. JACoW Geneva, Switzerland 978-3-95450-182-3 10.18429/JACoW-IPAC2017-TUPAB071 English 1488-1490 TUPAB071 Contribution to a conference proceedings 2017 2017-05 http://dx.doi.org/10.18429/JACoW-IPAC2017-TUPAB071 http://jacow.org/ipac2017/papers/tupab071.pdf In this paper, the first operation of a widely tunable 8-period undulator at terahertz (THz) frequency in Tsinghua University beamline was reported. Superradiate undulator radiation from sub-picosecond electron bunches compressed by chicane was observed. The measured radiation curve shows clearly that the radiation energy is proportional to the charge square, and the THz frequency can be changed from 0.4 THz to 10 THz with narrow-band spectrums. Our results demonstrate a high power and tunable coherent THz source, which could be useful for many applications in the future.