According to the characteristics of the energy transmission system of hydraulic offshore wind turbine, based on the linear friction distribution pipeline model,the mathematical equation of the large diameter fluid transmission distributed pipeline with constant diameter was established. The effects of the system input and pipeline parameters on system characteristics were studied.The amplitude ratios of the impeller torque and swash plate angle of variable pump to pipe inlet pressure have the same resonant point frequency，but the influence of the change of the swash plate angle on the inlet pressure is significantly higher than the impeller torque. The larger the inner diameter of the pipe is, the greater the pressure amplitude ratio is, especially in the low frequency range. The longer the pipeline is, the more the resonance point number is, the narrower the operating frequency band is. After the maximum resonance amplitude is reached for the first time, its resonance amplitude gradually decreases with the increasing frequency.