Abstract: As a new marine structure, the offshore floating-ring tourism platform has good development prospects. The water body within the floating-ring structure can be used as a floating yacht port. However, the increase in the water closure may also cause the water body resonance problem similar to the moon pool resonance, which can affect the conditions of wharf berthing stability. To study the influence of the platform draft, structural motion response and opening shape of the platform on the resonance response characteristics of the water body within the platform, the linear potential flow frequency domain method is applied. When the draft depth of the structure increases, the water body resonance frequency shifts toward the low frequency direction and the co-amplitude values of 0-2 order increase with the draft depth. The motion of the structure causes the water body resonance frequency shifting toward the high frequency direction and the resonance range of the structural motion response coincides with the range of water resonance frequency of 0-3 order. In addition, the pitch motion has a great influence on the distribution of resonance mode, while the influences of other freedom degrees are smaller. In order to suppress the inner water resonance, two schemes are proposed to add a thin plate or an artificial damping area at the surface line of the water. The results show that the adding of thin board can effectively reduce the water resonance in the range of high frequency and the adding of damping area can achieve the purpose of inhibiting water resonance within the entire range of wave frequency.