Based on capacitance change principle of dielectric electroactive polymer (EAP), a 3DOF soft position sensor is designed and implemented. The inner frame of the sensor can translate in in-plane and out-of-plane directions, which are used to measure the plane and normal displacement respectively. A geometrical model of the proposed sensor is developed and the relationship between the capacitance of the sensor and the displacement of the inner frame are deduced. A differential approach is used to measure the variation of the capacitance of the sensor, and the relationship between the capacitance difference of two opposite sensing cells and the in-plane displacement of the inner frame as well as the relationship between the capacitance of single cell and the out-of-plane displacement of the inner frame are analyzed. The measured inplane and out-of-plane displacement sensitivity are of 66.69 pF/mm and 0.47 pF/mm2 respectively, which agree well with the analytical results. The theoretical and experimental analyses verify the feasibility of the application of dielectric EAP to the position sensors.