Aiming at the establishment of a complete description of the adaptive motion curve of finger touching keys, a measurement method based on a Leap motion 3D sensor is proposed. According to capturing characteristics of the measurement method, firstly finger touch kinematics model is established before coordinate system is aligned step by step. Then the motion capture and the selection of motion feature points are carried out. The deviation angle is first introduced to transform the finger motion model from twodimensional space to threedimensional space. Finally, different fitting models are used to process the motion data of piano finger with 95% confidence bounds, and an adaptive function is established to describe the motion characteristics of finger playing. The adaptive function proves that the calibration of human hand fitting with different lengths can provide correct initial posture for the robot, which provides theoretical support for the adaptive identification system of finger touch motion curve in the teaching platform of piano playing education service robot.