Aiming at the high frequency vibration problem of the helicopter pedal， it is determined that the case of the vibration problem is the tail control stick local resonance caused by poor dynamic characteristics of the tail control stick through the flight vibration data analysis. In order to meet the requirements of installation， there is a small gap between the tail control stick and stick support， and this gap leads to the uncertainty of the retraining strength of the tail control stick， so it is necessary to carry out the sensitivity analysis of boundary constraints of the tail control stick. In this paper， the spring stiffness is used to characterize the effect of the small gap between tail control stick and stick support. The influence of boundary constraints on mounting frequency of the tail control stick is analyzed by tail control stick dynamic theoretical model based on Ritz method. Furthermore， the solution method is putted forward. Ground test and flight test show that the solution method can effectively improve the tail control stick high frequency vibration problem， and has a certain reference significance for the subsequent design and analysis of the control stick.