Abstract: In order to synchronize motion in physical human-robot interaction(pHRI),a control method based on online update of vector field is proposed and applied to the research on human-robot handshaking.Firstly,the polynomial expression approximation design is applied to endowing vector field of arbitrary attractor with self-oscillation characteristics.Secondly, input-output synchronization of the control system is realized by using online update design,and the degree of input-output synchronization can be modified by adjusting the oblivion parameter and load parameter in control system.Finally,the presented control method is used in human-robot handshaking experiment on a 7 DOF(degree of freedom)robot arm,and experimental results indicate the controller's validity.