Abstract: To develop the coupled-cavity linac (CCL), which works at 975 MHz, 3.7 MV/m of averaged electric field, and accelerating proton from 80 MeV to 300 MeV, the cooling structure was designed and the thermal analysis was carried out. Theoretical calculation was used to determine the dimension of the cooling structure and ANSYS was adopted to do the thermal analysis including thermal-structure-radio frequency coupling problem. The results show that the frequency shift is -0.427 MHz, and the sensitivity to temperature is 9.93 kHz/℃. It is within control range. In addition, the design and analysis method can be used to the cooling structure design of other types of resonant cavities.