Ultrasonic bonding was presented to bond the polymer micro devices in this paper.An ultrasonic precise bonding device was established and an adaptive pressure control method was also proposed.Considering the accuracies of shape and position of joining, a 60 kHz ultrasonic energy converter and a driving source were chosen to provide the higher frequency and lower amplitude for the micro device to reduce the damage of micro structure in bonding.Then, a high resolution stepper motor and a linear guide were chosen to control the longitudinal movement, and positioning accuracy of ultrasonic horn and to realize the real-time monitoring of the mechanical behaviors of polymer materials during bonding.Aiming at the problem of instable joining quality from the difference of surface roughness,an adaptive pressure control method based on material mechanical behavior feedback was proposed.Experiment results show that the stability of bonding is improved obviously by this bonding method and the precision bonding is achieved.