Abstract: This paper presents a six-axis rolotic wrist force sensor with a new non-diametric three-beam stsucture andits optimum design.Using this non-diametric three-beam rtrcuture the sensitivity and the calibration preci-sion of the wrist force sensor will be raised,the diametric effect will be improved as well as the axes of thesensor will put up more conveniently.The complex optimum design method can minimized the normal sectionsize of the strain and decrease its self-weight of the sensor on the premises of ensuring of the capacity loadand resolving power.This papes gives an effective way to design and research of multidementional force sen-sor.