This paper mainly introduces the structure and detecting theory of the six-dimension compliant wrist F/T sensor. The transition matrix between the moving base and the fixed base is set up using RPY method. The transition matrix is expressed by the position signals tested by the PSDs. On these bases,the formula of force vector and position vector is built. The force information can be acquired when the stiffness matrix is calibrated. Finally, this paper makes an introduction to the data acquisition and processing system for the sensor.