The invention relates to a cylinder-based humanoid robot lower limb device. Two knee joints are respectively arranged on two sides of the lower portion of a hip joint, the lower portions of the knee joints are connected with an ankle joint, four left adjusting cylinders are hinged below one side of an upper bracket of the hip joint, the lower portion of the other side is hinged to four right adjustment cylinders, the lower portions of the left adjusting cylinders are hinged to the surrounding of the left bracket, the lower portions of the right adjusting cylinders are hinged to the surroundingof the right bracket, the middle of the left bracket is connected to a right horizontal cylinder by a left support rod, the middle of the right bracket is connected to a left horizontal cylinder by aright support rod, and the left horizontal cylinder and the right horizontal cylinder are horizontally disposed and fixed to the upper bracket. The device has the advantages of compact structure, large moving range, clean explosion prevention and multi-degree of freedom, and can adopt different modes and real-time control according to the complex situation of the terrain, the need of steering andthe adjustment of the center of gravity.