To improve the landing capability of helicopters on complex terrain， this paper proposes an adaptive landing gear with ground contact sensing capability. Firstly， the posture adjustment movement form of the landing gear structure is optimized to ensure good motion adjustment capability and load-bearing capacity， so as to avoid the instability of the aircraft due to the change of landing gear posture during the landing process. Secondly， the landing posture can be adjusted without load according to the terrain step-difference， and a ground contact sensing principle is established by monitoring the elongation of actuator cylinder， which greatly reduces the dependence on various sensors and the high limit requirements for the landing site. The experimental results show that the adaptive landing gear can achieve vertical posture adjustment within 500 mm， and a singel landing gear can withstand a force of at least 2 000 N. The landing posture is not required to be perpendicular to the ground， and an inclination angle is allowed. As the inclination angle increases， the load capacity and the terrain adaptability of the landing gear increase accordingly.