Abstract: According to the structure and physiological properties of human respiratory system,a micro-robot system based on earthworm creeping motion principle is designed to move freely in trachea and two main bronchia.The mobile mechanism of the robot is flexibly actuated by a 3-DOF pneumatic rubber actuator.The structure and locomotion mechanism of the robot are described,and driving mechanics models of the robot system are set up and analyzed.Primary experiments have been done in a swine trachea,and preesures and temperatures in the trachea end are measured dynamically during mechanical ventilation.The primary studies show that the flexibly actuated robot system is capable of monitoring the respiratory parameters directly and dynamically during mechanical ventilation.