In view of the excessive simplification of single gate calculation model in safety assessment of radial gate, we compared and analyzed the static and dynamic characteristics between conventional single gate model and gate-dam system model considering friction of seal and the direct action between hinge and bracket under fully closed condition and instantaneously opening condition. Gate-dam system model was taken as standard. In static analysis, the maximum displacement and equivalent stress of main beam of lower frame for single gate model under fully closed condition are 108.5% and 67.1% larger, respectively. And internal force of arm is 52.8% larger. As a result, the lower frame of single gate model is very uneconomical. The maximum displacement and equivalent stress of main beam of upper frame for single gate model under instantaneously opening condition are 10.1% and 21.2% smaller, respectively. And the internal force of arm is 8.1% smaller. Therefore the upper frame of single gate model is very insecure. Moreover in dynamic analysis, the first ten natural frequencies of gate-dam system decreases 48% maximally with peripheral sealing and fluid-structure interaction, dodging the dominant frequency region of vibration excited by flow. It is beneficial to the dynamic stability of radial gate. Results show that reasonable model for safety assessment of radial gate should be gate-dam system model at check water level under instantaneously opening condition, which could ensure the validity of structural analysis and coordinate between safety and economy of gate structure.