In order to study the influence of the installation state on the natural frequency of the turbine bypass valve,a lateral vibration analysis model of the turbine bypass valve in the thermal full-flow test pipeline was established according to the double-beam structure assumption and the Euler-Bernoulli beam theory.Based on the sweep frequency method and the simple percussion method,a vibration test platform was built respectively to test the natural frequency of the turbine bypass valve in the two installation states of the rigid support of the body and the support of the pipeline.The fluid-structure interaction and modal simulation modules of ANSYS software were used to solve the natural frequencies of the turbine bypass valve for different pipeline support distances under the actual operating parameters.The research shows that the minimum natural frequencies of the turbine bypass valve with rigid support of the body acquired by the frequency sweep method,the simple percussion method and the numerical simulation method are 34.5 Hz,35 Hz and 35.41 Hz respectively,which meet the seismic frequency requirements of nuclear power valves.Pipeline support weakens the stiffness of the turbine bypass valve,which in turn reduces the natural frequency by about 7 Hz.The farther the pipeline support position is from the turbine bypass valve body,the greater the reduction is in natural frequency.The fluid-structure interaction effect of steam medium and turbine bypass valve reduces the natural frequency.Vibration suppression measures for turbine bypass valve should avoid the natural frequency and its multiplier close to the actual installation state,and the distance between the pipeline support and the valve can also be adjusted to increase or decrease the natural frequency,so as to achieve effective vibration suppression.