The invention belongs to the technical field of bionic robots, and particularly relates to an underactuated lightweight human-simulated five-finger dexterous hand. The underactuated lightweight human-simulated five-finger dexterous hand comprises a palm, five fingers, five finger bending and extension driving mechanisms, five rope transmission mechanisms and a thumb rotation driving mechanism, wherein the five fingers include a thumb, an index finger, a middle finger, a ring finger and a little finger which are installed on the palm in sequence by virtue of fixed seats; the five finger bendingand extension driving mechanisms are respectively installed on the five fixed seats and are respectively used for supplying power to the bending and extension of the five fingers; the five rope driving mechanisms are respectively installed in the five fingers and are connected with the corresponding finger bending and extension driving mechanisms, and the fingers are driven to bent and extend bythe finger bending and extension driving mechanisms through the rope driving mechanisms so as to form underactuation; and the thumb rotation driving mechanism is installed in the palm and is used fordriving the thumb to rotate. The underactuated lightweight human-simulated five-finger dexterous hand has the characteristics of the simple and compact structure, light weight, low cost, modular design, easiness in removal and replacement, high integration level, multiple degrees of freedom, small size, flexibility, good stability and the like, and the size of the underactuated lightweight human-simulated five-finger dexterous hand is similar to that of a hand.