A series of dynamic triaxle test on soft soil in Tangshan Binhai area was carried out to understand the horizontal dynamic characteristics of the soil around the offshore wind power pile foundation under wave load. The influence of confining pressure, dynamic stress amplitude and vibration frequency on horizontal dynamic characteristics of soft soil were studied. The results show that the horizontal dynamic strength of soft soil increases with the increase of confining pressure increases,and decreases with the increase of vibration. When the dynamic stress amplitude increases, the vibration times decreases. The horizontal dynamic strain ε_d increases with the increase of vibration frequency, and the larger the dynamic stress amplitude is, the more significant the growth is. The change agrees well with that of the Monismith model. The change of the horizontal dynamic modulus of soft soil is significantly influenced by the dynamic stress amplitude. When confining pressure decreases, dynamic modulus decreases. The Caofeidian soft soil has distinct structural horizontal dynamic characteristics. Under different confining pressures, the damping ratio shows an increasing trend when dynamic stress amplitude increases.