The invention provides a three-dimensional force sensor for a minimally invasive surgery robot. The sensor is a sensor array consisting of eight strain gages; the sensor array is arranged at the periphery of a hollow metal round bar close to the tail end of a manipulator, and divided into two regions for measuring a radial force and an axial force of the round bar; four rectangular planes which are orthogonal to one another and used for installing strain gages are machined in the radial force measurement region; the opposite faces of the four strain gages form two half bridges; each half bridge outputs three signal wires; the signal wires enter the hollow metal round bar from a wire-leading hole, and are led out from the connecting end of the manipulator; two pairs of strain gages are arranged at opposite positions of the axial force measurement region; the four strain gages are symmetrically arranged so as to form a Poisson bridge; the Poisson bridge outputs four signal wires; and the signal wires enter the round bar from the wire-leading hole and are led out from the connecting end of the manipulator. A metal foil for electromagnetic shielding is covered at the peripheries of the strain gages. The three-dimensional force sensor for the minimally invasive surgery robot has a simple structure, high sensitivity and low cost, and is easy to machine.