As a new type long-span gate, goggles gate's special mechanical structure result in its complex vibration characteristics. This article took Nanjing Sancha River double hole goggles gate as an example, revealed the relation between gate's vibrational frequency, gate opening and modal order when the gate is opened and closed in the flowing water, simulated the added mass in fluid-structure interaction by generalized Westergaard formula based on ANSYS modal analysis module, and researched on goggles gate's vibration characteristics. The results indicate that fluid-structure interaction which considered added mass conforms to real working condition in the low order modes. The gate is discovered that it has risk of resonance and dynamic instability. Gate structure and hoist mechanism need to be improved. The article can provide a reference for later design and optimization on goggles gate.