This paper presents a calibration method for a precision 6 - axis force sensor. By building an experimental platform, useing dynamometer that on the moving table apply an external force to the sensor, the senor can output difference voltage under the different force. Analyzing the relationship between the difference voltage with force and torque by numerical analysis method, then get the relation equation of them, use the calibration experiment result to analyze the force of pneumatic finger. The experiment result shows that the relationship between difference voltage with force and torque are linear; and there are great difference between fingertips force and finger base’s force.