To avoid damage or drop of micro objects in the gripping processing by a piezoelectric micro-gripper, the finger displacement and gripping force of the piezoelectric micro-gripper were detected by a resistance strain gauge. A novel gripper was presented by using flexible lever magnifying mechanism. The gripper has advantages of compact structure, integrated gripper body, translational motion of fingers, and the high sensitivity of fingertips. Based on bending theory of cantilever beam and finite element method, the strain characteristics of the elastic sensitive cell of the gripper were analyzed, the conclusion shows that the maximum strain part of the sensitive cell is closed to the bottom of the finger, and the displacement and gripping force of the fingers are proportional to the strain of the elastic sensitive cell. Then, relationships between the finger displacement, gripping force and the strain of the elastic sensitive cell were calibrated by experiments. The calibrating results show that both the two relationships are linear. Finally, the actual finger displacement and gripping force of the gripper were tested, and the tested results show that when a maximal voltage of 150 V is applied to the piezoelectric actuator, the maximal displacement of finger is 78.35 μm in no-load condition, and the gripping force of the fingers is 9.24 μN for holding a micro shaft with Φ0.3 mm and length of 8 mm.