Liu, W. Du, B. Huang, G. Lin, L. Shang, L. Song, W.B. JACoW Geneva, Switzerland 978-3-95450-182-3 10.18429/JACoW-IPAC2017-THPAB127 English 4020-4022 THPAB127 Contribution to a conference proceedings 2017 2017-05 http://dx.doi.org/10.18429/JACoW-IPAC2017-THPAB127 http://jacow.org/ipac2017/papers/thpab127.pdf The 24KW CW SSA (Solid-State Amplifier) is being developed to drive the 1.3GHz SC Linac used in a THz light source. The SSA adopts the compact all-in-one combining method ' cavity combiner, which is proposed and developed in recent years. This paper reports the R&D of the cavity combiner. The cavity combiner resonates in TM010 mode, coupling with 24 coaxial-connected 1kW amplifier modules. The cavity's electromagnetic characteristic is calculated by CST, and the mechanical structure including the input and output coupler has been designed.