A bionic knee joint transmission system and a bionic hip joint transmission system of a human body disclosed by the invention belong to the technical field of human body simulation and man-machine interfaces. Each system comprises a power unit, a transmission unit and a motion output unit, wherein the transmission unit comprises an input module and an output module. In the knee joint transmission system, the power unit and the motion output unit are located on the top and the bottom of the transmission unit respectively. In the hip joint transmission system, the power unit and the motion output unit are located inside the transmission unit. Tops and bottoms of the two joint transmission systems are equipped with interfaces which are connected to other bionic structural parts of the human body respectively; the input and output modules of the transmission units of the two joint transmission systems are connected to the corresponding power units and motion output units respectively; and the transmission units transform high-speed rotation input by the power units into low-speed rotation which satisfies knee joints and hip joints of the human body on human body vertical planes, and the motion output units transmit the low-speed rotation to the other bionic structural parts of the human body. The systems disclosed by the invention are matched with the other bionic structural parts of the human body, can ensure safety and have high motion transmission efficiency.